#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 q;
    cin >> q;
    for(int j =0; j<q; j++)
    {
        int n, x, y, minX, minY, maxX, maxY;
        cin >> n;
        int arrayX[n];
        int arrayY[n];
        cin >> x;
        cin >> y;
        arrayX[0] = minX = maxX = x;
        arrayY[0] = minY = maxY = y;
        for( int i=1; i<n;i++)
        {
            cin >> x;
            cin >> y;
            arrayX[i] = x;
            arrayY[i] = y;
            if( minX > x){
                minX = x;
            } else if( maxX < x){
                maxX = x;
            }
            if( minY > y){
                minY = y;
            } else if( maxY < y){
                maxY = y;
            }
        }
        // check is proper rectangle
        bool isProper = true;
        {
            for( int i=0; i<n;i++)
            {
                if( (arrayX[i] >= minX && arrayX[i] <= maxX) && (arrayY[i] == minY || arrayY[i] == maxY) ){
                    continue;
                }
                if( (arrayX[i] == minX || arrayX[i] == maxX) && (arrayY[i] >= minY && arrayY[i] <= maxY) )
                {
                    continue;
                } else {
                    isProper = false;
                    break;
                }
            }
        }
        if(isProper){
            cout << "YES" << endl;
        }else{
            cout << "NO" << endl;
        }
    }
    return 0;
}