#include <map>
#include <set>
#include <list>
#include <cmath>
#include <ctime>
#include <deque>
#include <queue>
#include <stack>
#include <string>
#include <bitset>
#include <cstdio>
#include <limits>
#include <vector>
#include <climits>
#include <cstring>
#include <cstdlib>
#include <fstream>
#include <numeric>
#include <sstream>
#include <iostream>
#include <algorithm>
#include <unordered_map>

using namespace std;


int main(){
  int n;
  cin >> n;
  int x1;
  int y1;
  cin >> x1 >> y1;
  for(int a0 = 1; a0 < n; a0++){
    int x2, y2;
    cin >> x2 >> y2;
    if (!(x2 == x1 || y2 == y1)) {
      cout << "NO" << endl;
      return 0;
    }
  }
  cout << "YES" << endl;
  return 0;
}