#include<bits/stdc++.h>
using namespace std;
#define offset 10002
bool a[20004][20004];
int main() {
  int t;
  cin >> t;
  while(t--) {
    int n;
    cin >> n;
    set <  int > sx,sy;
    for(int i = 0 ; i < n ; i++) {
      int u , v;
      cin >> u >> v;
      u += offset; v+= offset;
      a[u][v] = 1;
      sx.insert(u) ; sy.insert(v);
    }
    int cnt = 0;
    if(sx.size()  >= 3 && sy.size() >= 3) {
      cout <<"NO\n";
      continue;
    }
    cout << "YES\n";
  }
}