You are given n segments on the Ox-axis. You can drive a nail in any integer point on the Ox-axis line nail so, that all segments containing this point, are considered nailed down. If the nail passes through endpoint of some segment, this segment is considered to be nailed too. What is the smallest number of nails needed to nail all the segments down?

Input

The first line of the input contains single integer number n (1 ≤ n ≤ 1000) — amount of segments. Following n lines contain descriptions of the segments. Each description is a pair of integer numbers — endpoints coordinates. All the coordinates don't exceed 10000 by absolute value. Segments can degenarate to points.

Output

The first line should contain one integer number — the smallest number of nails needed to nail all the segments down. The second line should contain coordinates of driven nails separated by space in any order. If the answer is not unique, output any.

Examples

Input

2
0 2
2 5


Output

1
2 

Input

5
0 3
4 2
4 8
8 10
7 7


Output

3
7 10 3
#include <bits/stdc++.h>
using namespace std;
typedef long long int64;
typedef unsigned long long uint64;
const double pi = acos(-1.0);
const double eps = 1e-11;
template <class T>
inline void checkmin(T &a, T b) {
  if (b < a) a = b;
}
template <class T>
inline void checkmax(T &a, T b) {
  if (b > a) a = b;
}
template <class T>
inline T sqr(T x) {
  return x * x;
}
typedef pair<int, int> ipair;
template <class T>
inline T lowbit(T n) {
  return (n ^ (n - 1)) & n;
}
template <class T>
inline int countbit(T n) {
  return (n == 0) ? 0 : (1 + countbit(n & (n - 1)));
}
template <class T>
inline T gcd(T a, T b) {
  if (a < 0) return gcd(-a, b);
  if (b < 0) return gcd(a, -b);
  return (b == 0) ? a : gcd(b, a % b);
}
template <class T>
inline T lcm(T a, T b) {
  if (a < 0) return lcm(-a, b);
  if (b < 0) return lcm(a, -b);
  return a * (b / gcd(a, b));
}
template <class T>
inline T euclide(T a, T b, T &x, T &y) {
  if (a < 0) {
    T d = euclide(-a, b, x, y);
    x = -x;
    return d;
  }
  if (b < 0) {
    T d = euclide(a, -b, x, y);
    y = -y;
    return d;
  }
  if (b == 0) {
    x = 1;
    y = 0;
    return a;
  } else {
    T d = euclide(b, a % b, x, y);
    T t = x;
    x = y;
    y = t - (a / b) * y;
    return d;
  }
}
template <class T>
inline vector<pair<T, int> > factorize(T n) {
  vector<pair<T, int> > R;
  for (T i = 2; n > 1;) {
    if (n % i == 0) {
      int C = 0;
      for (; n % i == 0; C++, n /= i)
        ;
      R.push_back(make_pair(i, C));
    }
    i++;
    if (i > n / i) i = n;
  }
  if (n > 1) R.push_back(make_pair(n, 1));
  return R;
}
template <class T>
inline bool isPrimeNumber(T n) {
  if (n <= 1) return false;
  for (T i = 2; i * i <= n; i++)
    if (n % i == 0) return false;
  return true;
}
template <class T>
inline T eularFunction(T n) {
  vector<pair<T, int> > R = factorize(n);
  T r = n;
  for (int i = 0; i < R.size(); i++) r = r / R[i].first * (R[i].first - 1);
  return r;
}
const int MaxMatrixSize = 40;
template <class T>
inline void showMatrix(int n, T A[MaxMatrixSize][MaxMatrixSize]) {
  for (int i = 0; i < n; i++) {
    for (int j = 0; j < n; j++) cout << A[i][j];
    cout << endl;
  }
}
template <class T>
inline T checkMod(T n, T m) {
  return (n % m + m) % m;
}
template <class T>
inline void identityMatrix(int n, T A[MaxMatrixSize][MaxMatrixSize]) {
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) A[i][j] = (i == j) ? 1 : 0;
}
template <class T>
inline void addMatrix(int n, T C[MaxMatrixSize][MaxMatrixSize],
                      T A[MaxMatrixSize][MaxMatrixSize],
                      T B[MaxMatrixSize][MaxMatrixSize]) {
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) C[i][j] = A[i][j] + B[i][j];
}
template <class T>
inline void subMatrix(int n, T C[MaxMatrixSize][MaxMatrixSize],
                      T A[MaxMatrixSize][MaxMatrixSize],
                      T B[MaxMatrixSize][MaxMatrixSize]) {
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) C[i][j] = A[i][j] - B[i][j];
}
template <class T>
inline void mulMatrix(int n, T C[MaxMatrixSize][MaxMatrixSize],
                      T _A[MaxMatrixSize][MaxMatrixSize],
                      T _B[MaxMatrixSize][MaxMatrixSize]) {
  T A[MaxMatrixSize][MaxMatrixSize], B[MaxMatrixSize][MaxMatrixSize];
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++)
      A[i][j] = _A[i][j], B[i][j] = _B[i][j], C[i][j] = 0;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++)
      for (int k = 0; k < n; k++) C[i][j] += A[i][k] * B[k][j];
}
template <class T>
inline void addModMatrix(int n, T m, T C[MaxMatrixSize][MaxMatrixSize],
                         T A[MaxMatrixSize][MaxMatrixSize],
                         T B[MaxMatrixSize][MaxMatrixSize]) {
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) C[i][j] = checkMod(A[i][j] + B[i][j], m);
}
template <class T>
inline void subModMatrix(int n, T m, T C[MaxMatrixSize][MaxMatrixSize],
                         T A[MaxMatrixSize][MaxMatrixSize],
                         T B[MaxMatrixSize][MaxMatrixSize]) {
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++) C[i][j] = checkMod(A[i][j] - B[i][j], m);
}
template <class T>
inline T multiplyMod(T a, T b, T m) {
  return (T)((((int64)(a) * (int64)(b) % (int64)(m)) + (int64)(m)) %
             (int64)(m));
}
template <class T>
inline void mulModMatrix(int n, T m, T C[MaxMatrixSize][MaxMatrixSize],
                         T _A[MaxMatrixSize][MaxMatrixSize],
                         T _B[MaxMatrixSize][MaxMatrixSize]) {
  T A[MaxMatrixSize][MaxMatrixSize], B[MaxMatrixSize][MaxMatrixSize];
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++)
      A[i][j] = _A[i][j], B[i][j] = _B[i][j], C[i][j] = 0;
  for (int i = 0; i < n; i++)
    for (int j = 0; j < n; j++)
      for (int k = 0; k < n; k++)
        C[i][j] = (C[i][j] + multiplyMod(A[i][k], B[k][j], m)) % m;
}
template <class T>
inline T powerMod(T p, int e, T m) {
  if (e == 0)
    return 1 % m;
  else if (e % 2 == 0) {
    T t = powerMod(p, e / 2, m);
    return multiplyMod(t, t, m);
  } else
    return multiplyMod(powerMod(p, e - 1, m), p, m);
}
double dist(double x1, double y1, double x2, double y2) {
  return sqrt(sqr(x1 - x2) + sqr(y1 - y2));
}
double distR(double x1, double y1, double x2, double y2) {
  return sqr(x1 - x2) + sqr(y1 - y2);
}
template <class T>
T cross(T x0, T y0, T x1, T y1, T x2, T y2) {
  return (x1 - x0) * (y2 - y0) - (x2 - x0) * (y1 - y0);
}
int crossOper(double x0, double y0, double x1, double y1, double x2,
              double y2) {
  double t = (x1 - x0) * (y2 - y0) - (x2 - x0) * (y1 - y0);
  if (fabs(t) <= eps) return 0;
  return (t < 0) ? -1 : 1;
}
bool isIntersect(double x1, double y1, double x2, double y2, double x3,
                 double y3, double x4, double y4) {
  return crossOper(x1, y1, x2, y2, x3, y3) * crossOper(x1, y1, x2, y2, x4, y4) <
             0 &&
         crossOper(x3, y3, x4, y4, x1, y1) * crossOper(x3, y3, x4, y4, x2, y2) <
             0;
}
bool isMiddle(double s, double m, double t) {
  return fabs(s - m) <= eps || fabs(t - m) <= eps || (s < m) != (t < m);
}
bool isUpperCase(char c) { return c >= 'A' && c <= 'Z'; }
bool isLowerCase(char c) { return c >= 'a' && c <= 'z'; }
bool isLetter(char c) { return c >= 'A' && c <= 'Z' || c >= 'a' && c <= 'z'; }
bool isDigit(char c) { return c >= '0' && c <= '9'; }
char toLowerCase(char c) { return (isUpperCase(c)) ? (c + 32) : c; }
char toUpperCase(char c) { return (isLowerCase(c)) ? (c - 32) : c; }
template <class T>
string toString(T n) {
  ostringstream ost;
  ost << n;
  ost.flush();
  return ost.str();
}
int toInt(string s) {
  int r = 0;
  istringstream sin(s);
  sin >> r;
  return r;
}
int64 toInt64(string s) {
  int64 r = 0;
  istringstream sin(s);
  sin >> r;
  return r;
}
double toDouble(string s) {
  double r = 0;
  istringstream sin(s);
  sin >> r;
  return r;
}
template <class T>
void stoa(string s, int &n, T A[]) {
  n = 0;
  istringstream sin(s);
  for (T v; sin >> v; A[n++] = v)
    ;
}
template <class T>
void atos(int n, T A[], string &s) {
  ostringstream sout;
  for (int i = 0; i < n; i++) {
    if (i > 0) sout << ' ';
    sout << A[i];
  }
  s = sout.str();
}
template <class T>
void atov(int n, T A[], vector<T> &vi) {
  vi.clear();
  for (int i = 0; i < n; i++) vi.push_back(A[i]);
}
template <class T>
void vtoa(vector<T> vi, int &n, T A[]) {
  n = vi.size();
  for (int i = 0; i < n; i++) A[i] = vi[i];
}
template <class T>
void stov(string s, vector<T> &vi) {
  vi.clear();
  istringstream sin(s);
  for (T v; sin >> v; vi.push_bakc(v))
    ;
}
template <class T>
void vtos(vector<T> vi, string &s) {
  ostringstream sout;
  for (int i = 0; i < vi.size(); i++) {
    if (i > 0) sout << ' ';
    sout << vi[i];
  }
  s = sout.str();
}
template <class T>
struct Fraction {
  T a, b;
  Fraction(T a = 0, T b = 1);
  string toString();
};
template <class T>
Fraction<T>::Fraction(T a, T b) {
  T d = gcd(a, b);
  a /= d;
  b /= d;
  if (b < 0) a = -a, b = -b;
  this->a = a;
  this->b = b;
}
template <class T>
string Fraction<T>::toString() {
  ostringstream sout;
  sout << a << "/" << b;
  return sout.str();
}
template <class T>
Fraction<T> operator+(Fraction<T> p, Fraction<T> q) {
  return Fraction<T>(p.a * q.b + q.a * p.b, p.b * q.b);
}
template <class T>
Fraction<T> operator-(Fraction<T> p, Fraction<T> q) {
  return Fraction<T>(p.a * q.b - q.a * p.b, p.b * q.b);
}
template <class T>
Fraction<T> operator*(Fraction<T> p, Fraction<T> q) {
  return Fraction<T>(p.a * q.a, p.b * q.b);
}
template <class T>
Fraction<T> operator/(Fraction<T> p, Fraction<T> q) {
  return Fraction<T>(p.a * q.b, p.b * q.a);
}
struct node {
  int x, y;
};
node a[100005];
int ans[100005];
int ansn;
int n;
int cmp(node i, node j) {
  if (i.y < j.y)
    return 1;
  else if (i.y == j.y) {
    if (i.x < j.x) return 1;
  }
  return 0;
}
int main() {
  while (scanf("%d", &n) != EOF) {
    memset(a, 0, sizeof(a));
    memset(ans, 0, sizeof(ans));
    ansn = 0;
    for (int flag = 0; flag < n; flag++) {
      scanf("%d%d", &a[flag].x, &a[flag].y);
      if (a[flag].x > a[flag].y) {
        int tem = a[flag].x;
        a[flag].x = a[flag].y;
        a[flag].y = tem;
      }
    }
    sort(a, a + n, cmp);
    ans[ansn++] = a[0].y;
    for (int flag = 1; flag < n; flag++) {
      if (a[flag].x > ans[ansn - 1]) {
        ans[ansn++] = a[flag].y;
      }
    }
    printf("%d\n", ansn);
    printf("%d", ans[0]);
    for (int flag = 1; flag < ansn; flag++) {
      printf(" %d", ans[flag]);
    }
    printf("\n");
  }
}
