#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <utility>
#include <algorithm>

using namespace std;

bool oneCase(unsigned int N) {
   int r,c, maxR, minR, maxC, minC;
   if (2 != scanf("%d %d", &r, &c)) { return false; }
   minR = maxR = r;
   minC = maxC = c;
   vector<pair<int, int>> vals;
   vals.push_back({r,c});
   for (auto n=1; n < N; ++n) {
       if (2 == scanf("%d %d", &r, &c)) { 
           if (r < minR) { minR = r; } 
           if (r > maxR) { maxR = r; } 
           if (c < minC) { minC = c; } 
           if (c > maxC) { maxC = c; }
           vals.push_back({r,c});
       }
   }
   for (const auto &v : vals) {
      if (minR < v.first  && v.first < maxR && 
          minC < v.second && v.second < maxC) { return false; }
   }
   return true;
}

int main() {
    unsigned int m,M,N;
    if (1 != scanf("%u", &M)) { return 1; }
    for (m=0; m < M; ++m) {
       if (1 == scanf("%u", &N)) {
           puts(oneCase(N) ? "YES" : "NO");
       }
    }
    return 0;
}