#include <cmath>

#include <algorithm>
#include <iostream>
#include <vector>
#include <map>
using namespace std;
int n;
int x[110], y[110];

bool test() {
    map<int,int> X;
    map<int,int> Y;
    for (int i = 1; i <= n; ++i) {
        X[x[i]]++;
        Y[y[i]]++;
    }
    int minx = X.begin()->first;
    int maxx = X.rbegin()->first;
    int miny = Y.begin()->first;
    int maxy = Y.rbegin()->first;
    for (int i = 1; i <= n; ++i) {
        if (x[i] == maxx || x[i] == minx) {
            if (!(miny <= y[i] && y[i] <= maxy))
                return false;
        } else if (y[i] == maxy || y[i] == miny) {
            if (!(minx <= x[i] && x[i] <= maxx))
                return false;
        } else return false;
    }
    return true;
}

int main() {
    // freopen("test.in", "r", stdin);
    int q;
    cin >> q;
    for (int i = 1; i <= q; ++i) {
        cin >> n;
        for (int i = 1; i <= n; ++i) {
            cin >> x[i] >> y[i];
        }
        bool ok = test();
        if (ok)
            cout << "YES";
        else cout << "NO";
        cout << "\n";
    }
}