#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;

typedef long long LL;
int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    LL q,n,x,y,i;
    cin >> q;
    while(q--)
    {
       cin >> n;
      LL   max_x= -1000000,max_y = -1000000,min_x = 1000000,min_y = 100000,flag = 1,b,h,i;
      LL a[n+1][2];
       for(i = 0;i < n;i++)
       {
          cin >> x >> y;
          a[i][0] = x;
          a[i][1] = y;
          if(x > max_x)
            max_x = x;
          if(x < min_x)
            min_x = x;
          if(y < min_y)
            min_y = y;
          if(y > max_y)
             max_y = y;
       }
        b = max_x - min_x;
        h = max_y - min_y;
        if(n < 3)
            cout << "YES" << endl;
        else
        {
                flag = 1;
                for(i = 0; i < n;i++)
                {
                    if(a[i][0] == max_x || a[i][0] == min_x)
                    {
                        continue;
                    }
                    else if(a[i][1] == min_y || a[i][1] == max_y)
                    continue;
                    else
                    {
                        flag = 0;
                        break;
                    }
                }
                if(flag)
                cout << "YES" << endl;
                else
                cout << "NO" << endl;
        }

    }
    return 0;
}