#include <bits/stdc++.h>
using namespace std;


int main() {
    int t,n,x,y;
    cin>>t;
    while(t--){
        cin>>n;
        int X[n];
        int Y[n];
        pair<int,int> P[n];
        for(int i=0;i<n;i++){
            cin>>X[i]>>Y[i];
            P[i] = make_pair(X[i],Y[i]);
        }
        sort(X,X+n);
        sort(Y,Y+n);
        int xmin = X[0];
        int xmax = X[n-1];
        int ymin = Y[0];
        int ymax = Y[n-1];
        string ans = "YES";
        for(int i=0;i<n;i++){
            if(!(((P[i].first==xmin||P[i].first==xmax)&&(P[i].second>=ymin && P[i].second<=ymax)) || ((P[i].second==ymin||P[i].second==ymax)&&(P[i].first>=xmin && P[i].first<=xmax)))){
                ans = "NO";
                break;
            }
        }
        cout<<ans<<endl;
    }
    return 0;
}