#include <stdio.h>
#include <sstream>
#include <string.h>
#include <vector>
#include <map>
#include <algorithm>
#include <utility>
#include <set>
#include <cctype>
#include <queue>
#include <stack>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <deque>
#include <limits>
#include <iomanip>
#include <ctype.h>
#include <unordered_map>
#define _USE_MATH_DEFINES
#include <iostream>
#include <math.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, char> pic;
#define bit(x,v) ((ll)x << v)

const ll INF = 1000000007;
const int MAX = 210000;
const int MOD = 1000000007;

long long fac[MAX], finv[MAX], inv[MAX];
void COMinit() {
	fac[0] = fac[1] = 1;
	finv[0] = finv[1] = 1;
	inv[1] = 1;
	for (int i = 2; i < MAX; i++) {
		fac[i] = fac[i - 1] * i % MOD;
		inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
		finv[i] = finv[i - 1] * inv[i] % MOD;
	}
}

// 二項係数計算
long long COM(int n, int k) {
	if (n < k) return 0;
	if (n < 0 || k < 0) return 0;
	return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}

ll gcd(ll a, ll b) {
	if (b == 0) return a;
	return gcd(b, a % b);
}
int pr[100010];
void uini(int n) {
	for (size_t i = 0; i <= n; i++)
	{
		pr[i] = i;
	}
}

int parent(int x) {
	if (x == pr[x]) return x;
	return pr[x] = parent(pr[x]);
}

bool unit(int x, int y) {
	int px = parent(x);
	int py = parent(y);

	if (px == py) return false;
	if (px < py) {
		pr[py] = px;
	}
	else {
		pr[px] = py;
	}
	return true;
}

ll bit[200010];
int max_n = 200000;
int pm = 0;
void add(int x) {

	while (max_n >= x)
	{
		bit[x]++;
		x += x & -x;
	}
}
void sub(int x) {
	while (max_n >= x)
	{
		bit[x]--;
		x += x & -x;
	}
}
ll merge(ll *a, int left, int mid, int right) {
	ll n1 = mid - left;
	ll n2 = right - mid;
	vector<int> L(n1 + 1);
	vector<int> R(n2 + 1);
	for (size_t i = 0; i < n1; i++)
	{
		L[i] = a[left + i];
	}
	for (size_t i = 0; i < n2; i++)
	{
		R[i] = a[mid + i];
	}

	L[n1] = INF;
	R[n2] = INF;
	ll i = 0;
	ll j = 0;
	ll r = 0;
	for (size_t k = left; k < right; k++)
	{
		if (L[i] <= R[j]) {
			a[k] = L[i];
			i++;
		}
		else {
			a[k] = R[j];
			r += n1 - i;
			j++;
		}
	}
	return r;
}
ll merge2(pair<int, char> *a, int left, int mid, int right) {
	ll n1 = mid - left;
	ll n2 = right - mid;
	vector<pair<int, char>> L(n1 + 1);
	vector<pair<int, char>> R(n2 + 1);
	for (size_t i = 0; i < n1; i++)
	{
		L[i] = a[left + i];
	}
	for (size_t i = 0; i < n2; i++)
	{
		R[i] = a[mid + i];
	}

	L[n1] = make_pair(INF, ' ');
	R[n2] = make_pair(INF, ' ');
	ll i = 0;
	ll j = 0;
	ll r = 0;
	for (size_t k = left; k < right; k++)
	{
		if (L[i].first <= R[j].first) {
			a[k] = L[i];
			i++;
		}
		else {
			a[k] = R[j];
			r += n1 - i;
			j++;
		}
	}
	return r;
}
ll mergeSort2(pair<int, char> *a, int left, int right) {
	ll res = 0;
	if (left + 1 < right) {
		int mid = (left + right) / 2;
		res = mergeSort2(a, left, mid);
		res += mergeSort2(a, mid, right);
		res += merge2(a, left, mid, right);
	}
	return res;
}
ll mergeSort(ll *a, int left, int right) {
	ll res = 0;
	if (left + 1 < right) {
		int mid = (left + right) / 2;
		res = mergeSort(a, left, mid);
		res += mergeSort(a, mid, right);
		res += merge(a, left, mid, right);
	}
	return res;
}
int partition(pair<int, char> *a, int p, int r) {
	pair<int, char> x = a[r];
	int i = p - 1;
	for (size_t j = p; j < r; j++)
	{
		if (a[j].first <= x.first) {
			i++;
			swap(a[i], a[j]);
		}
	}
	swap(a[i + 1], a[r]);
	return i + 1;
}
void quick(pair<int, char> *a, int p, int r) {
	if (p < r) {
		int q = partition(a, p, r);
		quick(a, p, q - 1);
		quick(a, q + 1, r);
	}
}

int n;
vector<pii> es[100010];
int ci = 0;
ll P[1000010];
struct Node {
	int key;
	int priority;
	Node *parent, *left, *right;
	Node(int key, int priority);
	Node() {}
};
Node NIL;
Node::Node(int key, int priority) : key(key), priority(priority) {
	left = &NIL;
	right = &NIL;
}
Node* root = new Node();
void cenrec(Node* k) {
	if (k->key == NIL.key) return;
	cenrec(k->left);
	cout << " " << k->key;
	cenrec(k->right);
}
void fastrec(Node* k)
{
	if (k->key == NIL.key) return;
	cout << " " << k->key;
	fastrec(k->left);
	fastrec(k->right);
}
void insert(Node* v) {
	Node* y = &NIL;
	Node* x = root;
	while (x->key != NIL.key)
	{
		y = x;
		if (v->key < x->key) {
			x = x->left;
		}
		else {
			x = x->right;
		}
	}
	v->parent = y;
	if (y->key == NIL.key) {
		root = v;
	}
	else if (v->key < y->key) {
		y->left = v;
	}
	else {
		y->right = v;
	}

}

Node* find(Node* k, ll v)
{
	if (k->key == NIL.key) return &NIL;
	if (k->key == v) return k;
	if (v < k->key) return find(k->left, v);
	return find(k->right, v);
}
void delp12(Node* x) {
	if (x->key == NIL.key)  return;
	Node* l = x->left;
	Node* r = x->right;
	Node* pr = x->parent;

	if (l->key == NIL.key
		&& r->key == NIL.key) {
		if (pr->left == x) {
			pr->left = &NIL;
		}
		else pr->right = &NIL;
	}
	else if (l->key != NIL.key) {
		if (pr->left == x) {
			pr->left = l;
		}
		else pr->right = l;
		l->parent = pr;
	}
	else if (r->key != NIL.key) {
		if (pr->left == x) {
			pr->left = r;
		}
		else pr->right = r;
		r->parent = pr;
	}
}
Node* get_next(Node* k) {
	if (k->key == NIL.key) return &NIL;
	Node* res = get_next(k->left);
	if (res->key != NIL.key) return res;
	return k;
}
void del(Node* x) {

	if (x->key == NIL.key) return;
	Node* l = x->left;
	Node* r = x->right;
	Node* pr = x->parent;

	if (l->key != NIL.key && r->key != NIL.key) {
		Node* nex = get_next(r);
		x->key = nex->key;
		delp12(nex);
	}
	else {
		delp12(x);
	}
}
Node* rightRotate(Node *t) {
	Node* s = t->left;
	t->left = s->right;
	s->right = t;
	return s;
}
Node* leftRotate(Node *t) {
	Node* s = t->right;
	t->right = s->left;
	s->left = t;
	return s;
}
Node* _insert(Node *t, int key, int priority) {
	if (t->key == NIL.key) {
		return new Node(key, priority);
	}
	if (key == t->key) {
		return t;
	}

	if (key < t->key) {
		t->left = _insert(t->left, key, priority);
		if (t->priority < t->left->priority) {
			t = rightRotate(t);
		}
	}
	else {
		t->right = _insert(t->right, key, priority);
		if (t->priority < t->right->priority) {
			t = leftRotate(t);
		}
	}
	return t;
}
Node* delete1(Node* t, int key);
Node* _delete(Node *t, int key) {
	if (t->left->key == NIL.key && t->right->key == NIL.key) {
		return &NIL;
	}
	else if (t->left->key == NIL.key) {
		t = leftRotate(t);
	}
	else if (t->right->key == NIL.key) {
		t = rightRotate(t);
	}
	else
	{
		if (t->left->priority > t->right->priority) {
			t = rightRotate(t);
		}
		else
			t = leftRotate(t);
	}
	return delete1(t, key);
}
Node* delete1(Node* t, int key) {
	if (t->key == NIL.key) {
		return &NIL;
	}
	if (key < t->key) {
		t->left = delete1(t->left, key);
	}
	else if (key > t->key) {
		t->right = delete1(t->right, key);
	}
	else return _delete(t, key);
	return t;
}
int H;
int left(int i) {
	return i * 2 + 1;
}
int right(int i) {
	return i * 2 + 2;
}

ll heap[2000010];
void maxHeapify(int i) {
	int l = left(i);
	int r = right(i);
	int largest = 0;
	if (l < H && heap[l] > heap[i])
		largest = l;
	else
		largest = i;
	if (r < H && heap[r] > heap[largest])
		largest = r;

	if (largest != i) {
		swap(heap[i], heap[largest]);
		maxHeapify(largest);
	}
}
int pare(int i) {
	return (i - 1) / 2;
}
void raise(int i) {
	int l = pare(i);
	if (l < 0) return;

	if (heap[l] < heap[i]){
		swap(heap[i], heap[l]);
		raise(l);
	}
}
void minHeapify(int i) {
	int l = left(i);
	int r = right(i);
	int minimam = 0;
	if (l < H && heap[l] < heap[i])
		minimam = l;
	else
		minimam = i;
	if (r < H && heap[r] < heap[minimam])
		minimam = r;

	if (minimam != i) {
		swap(heap[i], heap[minimam]);
		minHeapify(minimam);
	}
}
void buildMaxHeap() {
	for (int i = H/2; i >= 0; i--)
	{
		maxHeapify(i);
	}
}
ll lcs(string s1, string s2) {
	ll dp[1010][1010];
	memset(dp, 0, sizeof(dp));
	int s1l = s1.size();
	int s2l = s2.size();
	for (size_t i = 1; i <= s1l; i++)
	{
		for (size_t j = 1; j <= s2l; j++)
		{
			if (s1[i - 1] == s2[j - 1]) {
				dp[i][j] = dp[i - 1][j - 1] + 1;
			}
			else {
				dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);

			}
		}
	}
	return dp[s1l][s2l];
}
struct edge {
	ll to, cap, rev;
	edge(int to,int cap,int rev) : to(to),cap(cap),rev(rev){}
};
vector<edge> ed[100010];
void addedge(int f, int t, int c) {
	ed[f].push_back(edge(t, c, ed[t].size()));
	ed[t].push_back(edge(f, 0, ed[f].size() - 1));
}
vector<int> es2[100010];

ll d[100010];
void dij(int x) {

	d[x] = 0;
	priority_queue<pll, vector<pll>, greater<pll>> q;
	q.push(pll(0, x));
	while (!q.empty())
	{
		pll p = q.top();
		q.pop();
		if (d[p.second] < p.first) continue;
		for (auto v : ed[p.second]) {
			if (d[v.to] > d[p.second] + v.cap) {
				d[v.to] = d[p.second] + v.cap;
				q.push(pll(d[v.to], v.to));
			}
		}
	}
}


int tb[5][5];
int ex[5][5];
pair<int, int> mdv[16];
int check() {
	int p = 1;
	int wc = 0;
	for (size_t i = 0; i < 4; i++)
	{
		for (size_t j = 0; j < 4; j++)
		{
			if (tb[i][j] != p) wc++;
			p++;
			p %= 16;
		}
	}
	return wc;
}

int lim = 45;
int md = 0;
int dx[] = { -1,0,1,0 };
int dy[] = { 0,-1,0,1 };
int res = INF;
int calcMd(int x, int y, int v) {

	return abs(mdv[v].first - x) + abs(mdv[v].second - y);
}
void rec(int x, int y, int deep) {

	if (deep >= res) return;
	if (deep > lim) return ;
	if (check() == 0) {
		res = deep;
		return;
	}

	for (size_t i = 0; i < 4; i++)
	{
		if (deep >= res) return;
		int tx = x + dx[i], ty = y + dy[i];
		if (tx < 0 || ty < 0 || tx >= 4 || ty >= 4) continue;
		int bef = calcMd(tx, ty, tb[tx][ty]);
		swap(tb[tx][ty], tb[x][y]);
		int af = calcMd(x, y, tb[x][y]);
		if (deep + md - bef + af <= lim) {
			md -= bef;
			md += af;
			rec(tx, ty, deep + 1);
			md += bef;
			md -= af;
			for (size_t j = 0; j < 4; j++)
			{
				for (size_t k = 0; k < 4; k++)
				{
					
					cout << " " << tb[j][k];
				}
				cout << endl;
			}
		}
		swap(tb[tx][ty], tb[x][y]);

	}
}
double leng(double x1, double x2, double y1, double y2) {
	return sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
}


double calc(double x1, double x2, double x3, double y1, double y2, double y3) {

	double high = 1;
	double low = 0;
	if (x1 > x2) {
		swap(x1, x2);
		swap(y1, y2);
	}
	double a = (y2 - y1) / (x2 - x1);
	double l1 = leng(x1,x3,y1,y3);
	double lp = leng(x2, x3, y2, y3);
	double c = y2 - a * x2;
	double b = x2 - x1;
	double miny = min(y1, y2);
	double maxy = max(y1, y2);
	int count = 0;
	double r = 0;
	double r2 = INF;
	while (count < 10000)
	{
		double mid = (high + low) / 2.0;
		double x4 = b * mid + x1;
		double y4 = x4 * a + c;
		double l2 = leng(x1, x4, y1, y4);
		double l3 = leng(x3, x4, y3, y4);
		double l4 = leng(x2, x4, y2, y4);

		double ss = (l1 + l2 + l3) / 2.0;
		double S = sqrt(ss * (ss - l1) * (ss - l2) * (ss - l3));

		double ss2 = (l4 + lp + l3) / 2.0;
		double S2 = sqrt(ss2 * (ss2 - l4) * (ss2 - lp) * (ss2 - l3));
		r = (2 * S) / (l1 + l2 + l3);
		r2 = (2 * S2) / (l4 + lp + l3);
		if (r < r2 ) {
			low = mid;
		}
		else if(r > r2){
			high = mid;
		}
		else {
			break;
		}
		count++;
	}
	return r2;
}
void solv() {

	//int sx, sy;
	//int c = 1;
	//for (size_t i = 0; i < 4; i++)
	//{	
	//	for (size_t j = 0; j < 4; j++)
	//	{
	//		ex[i][j] = c % 16;
	//		mdv[c].first = i;
	//		mdv[c].second = j;
	//		c++;
	//	}
	//}
	//for (size_t i = 0; i < 4; i++)
	//{
	//	for (size_t j = 0; j < 4; j++)
	//	{
	//		cin >> tb[i][j];
	//		md += calcMd(i, j, tb[i][j]);
	//		if (tb[i][j] == 0) {
	//			sx = i;
	//			sy = j;
	//		}
	//	}
	//}
	//lim = md;
	//while (res == INF)
	//{
	//	rec(sx, sy, 0);
	//	lim += 2;
	//}
	//cout << res << endl;
	int n;
	cin >> n;
	int tb[100010];
	memset(tb, 0, sizeof(tb));
	int pos = 1;
	tb[pos] = 1;
	int q;
	cin >> q;

	for (size_t i = 0; i < q; i++)
	{
		tb[pos - 1] = 2;
		tb[pos + 1] = 2;
		int a, b;
		cin >> a >> b;
		if (tb[a] == 1) {
			pos = b;
		}
		else if (tb[b] == 1) pos = a;
		swap(tb[a], tb[b]);
	}
	tb[pos -1] = 2;
	tb[pos + 1] = 2;
	int res = 0;
	for (size_t i = 1; i <= n; i++)
	{
		res += tb[i] != 0;
	}
	cout << res << endl;
}

int main() {
	//	COMinit();
	solv();
	return 0;
}

### Prompt

Your task is to create a cpp solution to the following problem:

You have N cups and 1 ball.

The cups are arranged in a row, from left to right.

You turned down all the cups, then inserted the ball into the leftmost cup.

Then, you will perform the following Q operations:

* The i-th operation: swap the positions of the A_i-th and B_i-th cups from the left. If one of these cups contains the ball, the ball will also move.



Since you are a magician, you can cast a magic described below:

* Magic: When the ball is contained in the i-th cup from the left, teleport the ball into the adjacent cup (that is, the (i-1)-th or (i+1)-th cup, if they exist).



The magic can be cast before the first operation, between two operations, or after the last operation, but you are allowed to cast it at most once during the whole process.

Find the number of cups with a possibility of containing the ball after all the operations and possibly casting the magic.

Constraints

* 2 \leq N \leq 10^5
* 1 \leq Q \leq 10^5
* 1 \leq A_i < B_i \leq N

Input

The input is given from Standard Input in the following format:


N Q
A_1 B_1
A_2 B_2
:
A_Q B_Q


Output

Print the number of cups with a possibility of eventually containing the ball.

Examples

Input

10 3
1 3
2 4
4 5


Output

4


Input

20 3
1 7
8 20
1 19


Output

5

### Response

```cpp
#include <stdio.h>
#include <sstream>
#include <string.h>
#include <vector>
#include <map>
#include <algorithm>
#include <utility>
#include <set>
#include <cctype>
#include <queue>
#include <stack>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <deque>
#include <limits>
#include <iomanip>
#include <ctype.h>
#include <unordered_map>
#define _USE_MATH_DEFINES
#include <iostream>
#include <math.h>
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef pair<int, char> pic;
#define bit(x,v) ((ll)x << v)

const ll INF = 1000000007;
const int MAX = 210000;
const int MOD = 1000000007;

long long fac[MAX], finv[MAX], inv[MAX];
void COMinit() {
	fac[0] = fac[1] = 1;
	finv[0] = finv[1] = 1;
	inv[1] = 1;
	for (int i = 2; i < MAX; i++) {
		fac[i] = fac[i - 1] * i % MOD;
		inv[i] = MOD - inv[MOD % i] * (MOD / i) % MOD;
		finv[i] = finv[i - 1] * inv[i] % MOD;
	}
}

// 二項係数計算
long long COM(int n, int k) {
	if (n < k) return 0;
	if (n < 0 || k < 0) return 0;
	return fac[n] * (finv[k] * finv[n - k] % MOD) % MOD;
}

ll gcd(ll a, ll b) {
	if (b == 0) return a;
	return gcd(b, a % b);
}
int pr[100010];
void uini(int n) {
	for (size_t i = 0; i <= n; i++)
	{
		pr[i] = i;
	}
}

int parent(int x) {
	if (x == pr[x]) return x;
	return pr[x] = parent(pr[x]);
}

bool unit(int x, int y) {
	int px = parent(x);
	int py = parent(y);

	if (px == py) return false;
	if (px < py) {
		pr[py] = px;
	}
	else {
		pr[px] = py;
	}
	return true;
}

ll bit[200010];
int max_n = 200000;
int pm = 0;
void add(int x) {

	while (max_n >= x)
	{
		bit[x]++;
		x += x & -x;
	}
}
void sub(int x) {
	while (max_n >= x)
	{
		bit[x]--;
		x += x & -x;
	}
}
ll merge(ll *a, int left, int mid, int right) {
	ll n1 = mid - left;
	ll n2 = right - mid;
	vector<int> L(n1 + 1);
	vector<int> R(n2 + 1);
	for (size_t i = 0; i < n1; i++)
	{
		L[i] = a[left + i];
	}
	for (size_t i = 0; i < n2; i++)
	{
		R[i] = a[mid + i];
	}

	L[n1] = INF;
	R[n2] = INF;
	ll i = 0;
	ll j = 0;
	ll r = 0;
	for (size_t k = left; k < right; k++)
	{
		if (L[i] <= R[j]) {
			a[k] = L[i];
			i++;
		}
		else {
			a[k] = R[j];
			r += n1 - i;
			j++;
		}
	}
	return r;
}
ll merge2(pair<int, char> *a, int left, int mid, int right) {
	ll n1 = mid - left;
	ll n2 = right - mid;
	vector<pair<int, char>> L(n1 + 1);
	vector<pair<int, char>> R(n2 + 1);
	for (size_t i = 0; i < n1; i++)
	{
		L[i] = a[left + i];
	}
	for (size_t i = 0; i < n2; i++)
	{
		R[i] = a[mid + i];
	}

	L[n1] = make_pair(INF, ' ');
	R[n2] = make_pair(INF, ' ');
	ll i = 0;
	ll j = 0;
	ll r = 0;
	for (size_t k = left; k < right; k++)
	{
		if (L[i].first <= R[j].first) {
			a[k] = L[i];
			i++;
		}
		else {
			a[k] = R[j];
			r += n1 - i;
			j++;
		}
	}
	return r;
}
ll mergeSort2(pair<int, char> *a, int left, int right) {
	ll res = 0;
	if (left + 1 < right) {
		int mid = (left + right) / 2;
		res = mergeSort2(a, left, mid);
		res += mergeSort2(a, mid, right);
		res += merge2(a, left, mid, right);
	}
	return res;
}
ll mergeSort(ll *a, int left, int right) {
	ll res = 0;
	if (left + 1 < right) {
		int mid = (left + right) / 2;
		res = mergeSort(a, left, mid);
		res += mergeSort(a, mid, right);
		res += merge(a, left, mid, right);
	}
	return res;
}
int partition(pair<int, char> *a, int p, int r) {
	pair<int, char> x = a[r];
	int i = p - 1;
	for (size_t j = p; j < r; j++)
	{
		if (a[j].first <= x.first) {
			i++;
			swap(a[i], a[j]);
		}
	}
	swap(a[i + 1], a[r]);
	return i + 1;
}
void quick(pair<int, char> *a, int p, int r) {
	if (p < r) {
		int q = partition(a, p, r);
		quick(a, p, q - 1);
		quick(a, q + 1, r);
	}
}

int n;
vector<pii> es[100010];
int ci = 0;
ll P[1000010];
struct Node {
	int key;
	int priority;
	Node *parent, *left, *right;
	Node(int key, int priority);
	Node() {}
};
Node NIL;
Node::Node(int key, int priority) : key(key), priority(priority) {
	left = &NIL;
	right = &NIL;
}
Node* root = new Node();
void cenrec(Node* k) {
	if (k->key == NIL.key) return;
	cenrec(k->left);
	cout << " " << k->key;
	cenrec(k->right);
}
void fastrec(Node* k)
{
	if (k->key == NIL.key) return;
	cout << " " << k->key;
	fastrec(k->left);
	fastrec(k->right);
}
void insert(Node* v) {
	Node* y = &NIL;
	Node* x = root;
	while (x->key != NIL.key)
	{
		y = x;
		if (v->key < x->key) {
			x = x->left;
		}
		else {
			x = x->right;
		}
	}
	v->parent = y;
	if (y->key == NIL.key) {
		root = v;
	}
	else if (v->key < y->key) {
		y->left = v;
	}
	else {
		y->right = v;
	}

}

Node* find(Node* k, ll v)
{
	if (k->key == NIL.key) return &NIL;
	if (k->key == v) return k;
	if (v < k->key) return find(k->left, v);
	return find(k->right, v);
}
void delp12(Node* x) {
	if (x->key == NIL.key)  return;
	Node* l = x->left;
	Node* r = x->right;
	Node* pr = x->parent;

	if (l->key == NIL.key
		&& r->key == NIL.key) {
		if (pr->left == x) {
			pr->left = &NIL;
		}
		else pr->right = &NIL;
	}
	else if (l->key != NIL.key) {
		if (pr->left == x) {
			pr->left = l;
		}
		else pr->right = l;
		l->parent = pr;
	}
	else if (r->key != NIL.key) {
		if (pr->left == x) {
			pr->left = r;
		}
		else pr->right = r;
		r->parent = pr;
	}
}
Node* get_next(Node* k) {
	if (k->key == NIL.key) return &NIL;
	Node* res = get_next(k->left);
	if (res->key != NIL.key) return res;
	return k;
}
void del(Node* x) {

	if (x->key == NIL.key) return;
	Node* l = x->left;
	Node* r = x->right;
	Node* pr = x->parent;

	if (l->key != NIL.key && r->key != NIL.key) {
		Node* nex = get_next(r);
		x->key = nex->key;
		delp12(nex);
	}
	else {
		delp12(x);
	}
}
Node* rightRotate(Node *t) {
	Node* s = t->left;
	t->left = s->right;
	s->right = t;
	return s;
}
Node* leftRotate(Node *t) {
	Node* s = t->right;
	t->right = s->left;
	s->left = t;
	return s;
}
Node* _insert(Node *t, int key, int priority) {
	if (t->key == NIL.key) {
		return new Node(key, priority);
	}
	if (key == t->key) {
		return t;
	}

	if (key < t->key) {
		t->left = _insert(t->left, key, priority);
		if (t->priority < t->left->priority) {
			t = rightRotate(t);
		}
	}
	else {
		t->right = _insert(t->right, key, priority);
		if (t->priority < t->right->priority) {
			t = leftRotate(t);
		}
	}
	return t;
}
Node* delete1(Node* t, int key);
Node* _delete(Node *t, int key) {
	if (t->left->key == NIL.key && t->right->key == NIL.key) {
		return &NIL;
	}
	else if (t->left->key == NIL.key) {
		t = leftRotate(t);
	}
	else if (t->right->key == NIL.key) {
		t = rightRotate(t);
	}
	else
	{
		if (t->left->priority > t->right->priority) {
			t = rightRotate(t);
		}
		else
			t = leftRotate(t);
	}
	return delete1(t, key);
}
Node* delete1(Node* t, int key) {
	if (t->key == NIL.key) {
		return &NIL;
	}
	if (key < t->key) {
		t->left = delete1(t->left, key);
	}
	else if (key > t->key) {
		t->right = delete1(t->right, key);
	}
	else return _delete(t, key);
	return t;
}
int H;
int left(int i) {
	return i * 2 + 1;
}
int right(int i) {
	return i * 2 + 2;
}

ll heap[2000010];
void maxHeapify(int i) {
	int l = left(i);
	int r = right(i);
	int largest = 0;
	if (l < H && heap[l] > heap[i])
		largest = l;
	else
		largest = i;
	if (r < H && heap[r] > heap[largest])
		largest = r;

	if (largest != i) {
		swap(heap[i], heap[largest]);
		maxHeapify(largest);
	}
}
int pare(int i) {
	return (i - 1) / 2;
}
void raise(int i) {
	int l = pare(i);
	if (l < 0) return;

	if (heap[l] < heap[i]){
		swap(heap[i], heap[l]);
		raise(l);
	}
}
void minHeapify(int i) {
	int l = left(i);
	int r = right(i);
	int minimam = 0;
	if (l < H && heap[l] < heap[i])
		minimam = l;
	else
		minimam = i;
	if (r < H && heap[r] < heap[minimam])
		minimam = r;

	if (minimam != i) {
		swap(heap[i], heap[minimam]);
		minHeapify(minimam);
	}
}
void buildMaxHeap() {
	for (int i = H/2; i >= 0; i--)
	{
		maxHeapify(i);
	}
}
ll lcs(string s1, string s2) {
	ll dp[1010][1010];
	memset(dp, 0, sizeof(dp));
	int s1l = s1.size();
	int s2l = s2.size();
	for (size_t i = 1; i <= s1l; i++)
	{
		for (size_t j = 1; j <= s2l; j++)
		{
			if (s1[i - 1] == s2[j - 1]) {
				dp[i][j] = dp[i - 1][j - 1] + 1;
			}
			else {
				dp[i][j] = max(dp[i - 1][j], dp[i][j - 1]);

			}
		}
	}
	return dp[s1l][s2l];
}
struct edge {
	ll to, cap, rev;
	edge(int to,int cap,int rev) : to(to),cap(cap),rev(rev){}
};
vector<edge> ed[100010];
void addedge(int f, int t, int c) {
	ed[f].push_back(edge(t, c, ed[t].size()));
	ed[t].push_back(edge(f, 0, ed[f].size() - 1));
}
vector<int> es2[100010];

ll d[100010];
void dij(int x) {

	d[x] = 0;
	priority_queue<pll, vector<pll>, greater<pll>> q;
	q.push(pll(0, x));
	while (!q.empty())
	{
		pll p = q.top();
		q.pop();
		if (d[p.second] < p.first) continue;
		for (auto v : ed[p.second]) {
			if (d[v.to] > d[p.second] + v.cap) {
				d[v.to] = d[p.second] + v.cap;
				q.push(pll(d[v.to], v.to));
			}
		}
	}
}


int tb[5][5];
int ex[5][5];
pair<int, int> mdv[16];
int check() {
	int p = 1;
	int wc = 0;
	for (size_t i = 0; i < 4; i++)
	{
		for (size_t j = 0; j < 4; j++)
		{
			if (tb[i][j] != p) wc++;
			p++;
			p %= 16;
		}
	}
	return wc;
}

int lim = 45;
int md = 0;
int dx[] = { -1,0,1,0 };
int dy[] = { 0,-1,0,1 };
int res = INF;
int calcMd(int x, int y, int v) {

	return abs(mdv[v].first - x) + abs(mdv[v].second - y);
}
void rec(int x, int y, int deep) {

	if (deep >= res) return;
	if (deep > lim) return ;
	if (check() == 0) {
		res = deep;
		return;
	}

	for (size_t i = 0; i < 4; i++)
	{
		if (deep >= res) return;
		int tx = x + dx[i], ty = y + dy[i];
		if (tx < 0 || ty < 0 || tx >= 4 || ty >= 4) continue;
		int bef = calcMd(tx, ty, tb[tx][ty]);
		swap(tb[tx][ty], tb[x][y]);
		int af = calcMd(x, y, tb[x][y]);
		if (deep + md - bef + af <= lim) {
			md -= bef;
			md += af;
			rec(tx, ty, deep + 1);
			md += bef;
			md -= af;
			for (size_t j = 0; j < 4; j++)
			{
				for (size_t k = 0; k < 4; k++)
				{
					
					cout << " " << tb[j][k];
				}
				cout << endl;
			}
		}
		swap(tb[tx][ty], tb[x][y]);

	}
}
double leng(double x1, double x2, double y1, double y2) {
	return sqrt((x2 - x1) * (x2 - x1) + (y2 - y1) * (y2 - y1));
}


double calc(double x1, double x2, double x3, double y1, double y2, double y3) {

	double high = 1;
	double low = 0;
	if (x1 > x2) {
		swap(x1, x2);
		swap(y1, y2);
	}
	double a = (y2 - y1) / (x2 - x1);
	double l1 = leng(x1,x3,y1,y3);
	double lp = leng(x2, x3, y2, y3);
	double c = y2 - a * x2;
	double b = x2 - x1;
	double miny = min(y1, y2);
	double maxy = max(y1, y2);
	int count = 0;
	double r = 0;
	double r2 = INF;
	while (count < 10000)
	{
		double mid = (high + low) / 2.0;
		double x4 = b * mid + x1;
		double y4 = x4 * a + c;
		double l2 = leng(x1, x4, y1, y4);
		double l3 = leng(x3, x4, y3, y4);
		double l4 = leng(x2, x4, y2, y4);

		double ss = (l1 + l2 + l3) / 2.0;
		double S = sqrt(ss * (ss - l1) * (ss - l2) * (ss - l3));

		double ss2 = (l4 + lp + l3) / 2.0;
		double S2 = sqrt(ss2 * (ss2 - l4) * (ss2 - lp) * (ss2 - l3));
		r = (2 * S) / (l1 + l2 + l3);
		r2 = (2 * S2) / (l4 + lp + l3);
		if (r < r2 ) {
			low = mid;
		}
		else if(r > r2){
			high = mid;
		}
		else {
			break;
		}
		count++;
	}
	return r2;
}
void solv() {

	//int sx, sy;
	//int c = 1;
	//for (size_t i = 0; i < 4; i++)
	//{	
	//	for (size_t j = 0; j < 4; j++)
	//	{
	//		ex[i][j] = c % 16;
	//		mdv[c].first = i;
	//		mdv[c].second = j;
	//		c++;
	//	}
	//}
	//for (size_t i = 0; i < 4; i++)
	//{
	//	for (size_t j = 0; j < 4; j++)
	//	{
	//		cin >> tb[i][j];
	//		md += calcMd(i, j, tb[i][j]);
	//		if (tb[i][j] == 0) {
	//			sx = i;
	//			sy = j;
	//		}
	//	}
	//}
	//lim = md;
	//while (res == INF)
	//{
	//	rec(sx, sy, 0);
	//	lim += 2;
	//}
	//cout << res << endl;
	int n;
	cin >> n;
	int tb[100010];
	memset(tb, 0, sizeof(tb));
	int pos = 1;
	tb[pos] = 1;
	int q;
	cin >> q;

	for (size_t i = 0; i < q; i++)
	{
		tb[pos - 1] = 2;
		tb[pos + 1] = 2;
		int a, b;
		cin >> a >> b;
		if (tb[a] == 1) {
			pos = b;
		}
		else if (tb[b] == 1) pos = a;
		swap(tb[a], tb[b]);
	}
	tb[pos -1] = 2;
	tb[pos + 1] = 2;
	int res = 0;
	for (size_t i = 1; i <= n; i++)
	{
		res += tb[i] != 0;
	}
	cout << res << endl;
}

int main() {
	//	COMinit();
	solv();
	return 0;
}

```