#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
  int n, x, y, sx, sy;
  cin >> n;
  cin >> sx >> sy;
  bool isHor = true, isVer = true;
  while(--n) {
    cin >> x >> y;
    if(sx != x) isHor = false;
    if(sy != y) isVer = false;
  }
  cout << ((isHor || isVer) ? "YES" : "NO");
  return 0;
}