#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 t=0; t<q; t++){
        int n;
        cin >> n;
        int arr[n][2];
        int xArr[n];
        int yArr[n];
        for(int i=0; i<n; i++){
            cin >> arr[i][0];
            xArr[i] = arr[i][0];
            cin >> arr[i][1];
            yArr[i] = arr[i][1];
        }
    
        sort(xArr, xArr+n);
        sort(yArr, yArr+n);
        int minX = xArr[0];
        int maxX = xArr[n-1];
        int minY = yArr[0];
        int maxY = yArr[n-1];
    
        bool flag = true;
        for(int i=0; i<n; i++){
            int x = arr[i][0];
            int y = arr[i][1];
        
        if((y==minY)&&(x>=minX)&&(x<=maxX)){
            continue;
        }
          if((y==maxY)&&(x>=minX)&&(x<=maxX)){
            continue;
        }
            if((x==minX)&&(y>=minY)&&(y<=maxY)){
            continue;
        }
            if((x==maxX)&&(y>=minY)&&(y<=maxY)){
            continue;
        }
        flag = false;
        break;
        }
        if(flag == true){
        cout << "YES" << endl;
        }
    else {
        cout << "NO" << endl;
    }
    }
    
    
    return 0;
}