#include<bits/stdc++.h>

using namespace std;

const int kMaxN = 55;

int n, x, y;
pair<int,int> P[kMaxN];

bool can(int x0, int x1, int y0, int y1) {
  int maxx = max(P[x0].first, P[x1].first);
  int minx = min(P[x0].first, P[x1].first);
  int maxy = max(P[y0].second, P[y1].second);
  int miny = min(P[y0].second, P[y1].second);
  //cout<<maxx<<" "<<minx<<endl;
  for(int i=0; i<n; ++i) {
    if (P[i].first != P[x0].first && P[i].first != P[x1].first && P[i].second != P[y0].second && P[i].second != P[y1].second)
      return false;
    if (P[i].first > maxx || P[i].first < minx) {
      return false;
    }
    if (P[i].second > maxy || P[i].second < miny) {
      return false;
    }
    
  }
  return true;
}

int main() {
  int T;
  scanf("%d", &T);
  while (T--) {
    cin>>n;
    for(int i=0; i<n; ++i) {
      cin>>x>>y;
      P[i] = make_pair(x, y);
    }
    sort(P, P + n);
    bool ok = 0;
    for(int x0=0; x0<n; ++x0) {
      for(int x1=0; x1<n; ++x1) {
        for(int y0=0; y0<n; ++y0) {
          for(int y1=0; y1<n; ++y1) {
            if (can(x0, x1, y0, y1)) {
              ok = 1;
              break;
            }
          }
        }
      }
    }
    if (ok) puts("YES");
    else puts("NO");
    
  }
}