#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;
int arr[10000][2];

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int testCase;
    cin >> testCase;
    for(int i = 0; i < testCase; i++){
        int edges;
        cin >> edges;
        int minVal = 10000, minVal1 = 10000, maxVal = -10000,maxVal1=-10000;
        for(int k = 0; k < edges; k++){
            int a,b;
            cin >> a >> b;
            arr[k][0] = a;
            arr[k][1] = b;
            minVal = min(a,minVal);
            minVal1 = min(b,minVal1);
            maxVal = max(a,maxVal);
            maxVal1 = max(b,maxVal1);
        }
        bool flag = true;
        for(int k = 0; k < edges; k++){
            if((((arr[k][0] != minVal)&&(arr[k][0] != maxVal))&&((arr[k][1] != minVal1)&&(arr[k][1] != maxVal1)))&&flag){
                cout << "NO" << endl;
                flag = false;
            }
        }
        if(flag)
            cout << "YES" << endl;
        
    }
    return 0;
}