#include <bits/stdc++.h>

using namespace std;

typedef pair< int, int > Pi;
const int vy[] = {0, 1, 0, -1}, vx[] = {1, 0, -1, 0};


map< Pi, Pi > futon;
map< Pi, int > head;

bool check(const Pi &point)
{
  head[point] = 1;
  head[futon[point]] = -1;
  bool flag = true;
  for(int i = 0; i < 4 && flag; i++) {
    const int nx = point.first + vx[i], ny = point.second + vy[i];
    if(make_pair(nx, ny) == futon[point]) continue;
    if(head.find({nx, ny}) != head.end()) {
      if(head[{nx, ny}] == -1) flag = false;
    } else if(futon.find({nx, ny}) != futon.end()) {
      if(!check({nx, ny})) flag = false;
    }
  }

  for(int i = 0; i < 4 && flag; i++) {
    const int nx = futon[point].first + vx[i], ny = futon[point].second + vy[i];
    if(make_pair(nx, ny) == point) continue;
    if(head.find({nx, ny}) != head.end()) {
      if(head[{nx, ny}] == 1) flag = false;
    } else if(futon.find({nx, ny}) != futon.end()) {
      if(!check(futon[{nx, ny}])) flag = false;
    }
  }
  return (flag);
}


int main()
{
  int N, R[100];

  cin >> N;

  vector< pair< int, int > > vv;
  int a[100], b[100], c[100], d[100];
  for(int i = 0; i < N; i++) {
    int x1, y1, x2, y2;
    cin >> x1 >> y1 >> x2 >> y2;
    futon[{x1, y1}] = {x2, y2};
    futon[{x2, y2}] = {x1, y1};
  }
  sort(begin(vv), end(vv));

  while(!futon.empty()) {
    auto decide = *futon.begin();
    if(head.find(decide.first) == head.end()) {
      if(!check(decide.first)) break;
    }
    futon.erase(futon.begin());
  }
  if(futon.empty()) cout << "YES" << endl;
  else cout << "NO" << endl;


}