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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int i,q,n,x1,x2,y1,y2;
    const int inf = 1e8;
    cin >> q;
    
    while(q--)
    {
        cin >> n; x1 = y1 = inf; x2 = y2 = -inf;
        vector<int> x(n),y(n);
        for(i = 0; i < x.size(); i++)
        {
            cin >> x[i] >> y[i];
            x1 = min(x1,x[i]);
            y1 = min(y1,y[i]);
            x2 = max(x2,x[i]);
            y2 = max(y2,y[i]);
        }
        for(i = 0; i < x.size(); i++)
        {
            if(x[i] != x1 && x[i] != x2 && y[i] != y1 && y[i] != y2)
            {
                cout << "NO" << endl;
                break;
            }
        }
        if(i == x.size())cout << "YES" << endl;
        
    }
    return 0;
}