#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,m;
    cin>>q;
    int *f = new int[q];
    int i;
    for(i = 0; i<q;i++){
        f[i] = 1;
    }
    for(i =1; i<=q;i++){
        cin>>m;
        int n = 2;
        int **ptr = new int*[m];
        for(int i = 0; i < m; i++){
            ptr[i] = new int[2];
        }
        for(int j = 0;j<m;j++){
            cin>>(ptr[j][0])>>(ptr[j][1]);
        }
        int bigx=(ptr[0][0]);
        for(i =0;i<m;i++){
            if((ptr[i][0])>bigx){(ptr[i][0])=bigx;}
        }
        int smallx=(ptr[0][0]);
         for(i =0;i<m;i++){
            if((ptr[i][0])<smallx){(ptr[i][0])=smallx;}
        }
        int bigy=(ptr[0][1]);
        for(i =0;i<m;i++){
            if((ptr[i][1])>bigy){(ptr[i][1])=bigy;}
        }
        int smally=(ptr[0][1]);
         for(i =0;i<m;i++){
            if((ptr[i][1])<smally){(ptr[i][1])=smally;}
        }
        if(bigx==smallx||bigy==smally){f[q] = 1;}
        for(i = 0;i < m;i++){
            if((ptr[i][0]!=bigx)||(ptr[i][1]!=bigy)||(ptr[i][0]!=smallx)||(ptr[i][1]!=smally)){
                f[q] = 0;
            }
        }
            
    }
    for(i=0;i<q;i++){
        if(f[q]==0)
            cout<<"NO\n";
        else
            cout<<"YES\n";
    }
    return 0;
}