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

int main() {
    ll t,n,i,x,y,j;
    cin>>t;
    while(t--){
        cin>>n;
        vector<ll> vx,vy;
        for(i=0;i<n;i++){
            cin>>x>>y;
            vx.push_back(x);
            vy.push_back(y);
        }
        x = 1;
        if(n > 2){
            for(i=0;i<n;i++){
                for(j=0;j<n;j++){
                    if(i != j){
                        if(vx[i] - vx[j] == 0)
                            break;
                    }
                }
                if(j == n){
                    for(j=0;j<n;j++){
                        if(i != j){
                            if(vy[i] - vy[j] == 0)
                                break;
                        }
                    }
                    if(j == n){
                        x = 0;
                        break;
                    }
                }
                if(!x)
                    break;
            }
        }
        if(x)
            cout<<"YES"<<endl;
        else
            cout<<"NO"<<endl;
    }
    return 0;
}