#include <iostream>

int main()
{
  std::ios_base::sync_with_stdio(false);

  int n;
  std::cin >> n;

  int prev_t1, prev_t2;
  std::cin >> prev_t1 >> prev_t2;
  bool vert = true;
  bool hori = true;
  while(n-- && (vert || hori))
  {
    int t1, t2;
    std::cin >> t1 >> t2;
    if(t1 != prev_t1) vert = false;
    if(t2 != prev_t2) hori = false;
    if(!vert && !hori)
    {
      std::cout << "NO\n";
      return 0;
    }
  }
  std::cout << "YES\n";
}