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

const int MXN = 12, INF = 1e9;

int N,Q;
int X[MXN],Y[MXN];

inline int gcd(int a,int b){
    if(b == 0) return a;
    return gcd(b,a % b);
}

int main() {
    cin >> Q;
    while(Q--){
        cin >> N;
        map <int,int> H,V;
        map < pair< pair<int,int>,int >, int> Any;
        int X1,Y1,X2,Y2;
        X1 = Y1 = INF;
        X2 = Y2 = -INF;
        for(int i = 1;i <= N;++i){
            cin >> X[i] >> Y[i];
            X1 = min(X1,X[i]);
            Y1 = min(Y1,Y[i]);
            X2 = max(X2,X[i]);
            Y2 = max(Y2,Y[i]);
        }
        bool ok = true;
        for(int i = 1;i <= N;++i){
            if(X[i] == X1){
                ok &= (Y[i] >= Y1 && Y[i] <= Y2);
            } else if(Y[i] == Y1){
                ok &= (X[i] >= X1 && X[i] <= X2);
            } else if(X[i] == X2){
                ok &= (Y[i] >= Y1 && Y[i] <= Y2);                
            } else if(Y[i] == Y2){
                ok &= (X[i] >= X1 && X[i] <= X2);
            } else {
                ok = false;
            }
        }
        if(ok) cout << "YES\n";
        else cout << "NO\n";
    }
    return 0;
}