#include <bits/stdc++.h>
#define REP(i,n) for(int i=0;i<int(n);i++)
#define ALL(v) (v).begin(),(v).end()
#define pb push_back
#define show(x) cout<< #x << " = " << x << endl
using namespace std;

typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

int vx[]={0,0,-1,1};
int vy[]={1,-1,0,0};
int dx[]={1,0,-1,1,-1,1,0,-1};
int dy[]={1,1,1,0,0,-1,-1,-1};

int gcd(int a,int b){return b?gcd(b,a%b):a;}
int lcm(int a,int b){return a*b/gcd(a,b);}	

const ll mod=1e9+7;
const int INF=INT_MAX/2;
const int N_MAX=100010;

int main(){
	int n;
	cin>>n;
	vector<int> l(n+1),r(n+1);
	REP(i,n)cin>>l[i]>>r[i];
	l[n]=r[n]=0;
	sort(l.begin(),l.end(),greater<int>());
	sort(r.begin(),r.end());
	ll ans=0;
	REP(i,n+1){
		if(l[i]>r[i])ans+=2*(l[i]-r[i]);
	}
	cout<<ans<<endl;
	return 0;
}

### Prompt

Please provide a Cpp coded solution to the problem described below:

Takahashi and Aoki will play a game with a number line and some segments. Takahashi is standing on the number line and he is initially at coordinate 0. Aoki has N segments. The i-th segment is [L_i,R_i], that is, a segment consisting of points with coordinates between L_i and R_i (inclusive).

The game has N steps. The i-th step proceeds as follows:

* First, Aoki chooses a segment that is still not chosen yet from the N segments and tells it to Takahashi.
* Then, Takahashi walks along the number line to some point within the segment chosen by Aoki this time.



After N steps are performed, Takahashi will return to coordinate 0 and the game ends.

Let K be the total distance traveled by Takahashi throughout the game. Aoki will choose segments so that K will be as large as possible, and Takahashi walks along the line so that K will be as small as possible. What will be the value of K in the end?

Constraints

* 1 ≤ N ≤ 10^5
* -10^5 ≤ L_i < R_i ≤ 10^5
* L_i and R_i are integers.

Input

Input is given from Standard Input in the following format:


N
L_1 R_1
:
L_N R_N


Output

Print the total distance traveled by Takahashi throughout the game when Takahashi and Aoki acts as above. It is guaranteed that K is always an integer when L_i,R_i are integers.

Examples

Input

3
-5 1
3 7
-4 -2


Output

10


Input

3
1 2
3 4
5 6


Output

12


Input

5
-2 0
-2 0
7 8
9 10
-2 -1


Output

34

### Response

```cpp
#include <bits/stdc++.h>
#define REP(i,n) for(int i=0;i<int(n);i++)
#define ALL(v) (v).begin(),(v).end()
#define pb push_back
#define show(x) cout<< #x << " = " << x << endl
using namespace std;

typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;

int vx[]={0,0,-1,1};
int vy[]={1,-1,0,0};
int dx[]={1,0,-1,1,-1,1,0,-1};
int dy[]={1,1,1,0,0,-1,-1,-1};

int gcd(int a,int b){return b?gcd(b,a%b):a;}
int lcm(int a,int b){return a*b/gcd(a,b);}	

const ll mod=1e9+7;
const int INF=INT_MAX/2;
const int N_MAX=100010;

int main(){
	int n;
	cin>>n;
	vector<int> l(n+1),r(n+1);
	REP(i,n)cin>>l[i]>>r[i];
	l[n]=r[n]=0;
	sort(l.begin(),l.end(),greater<int>());
	sort(r.begin(),r.end());
	ll ans=0;
	REP(i,n+1){
		if(l[i]>r[i])ans+=2*(l[i]-r[i]);
	}
	cout<<ans<<endl;
	return 0;
}

```