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

bool checkRectangle(int x, int y, int tlx, int tly, int brx, int bry) {
    if (x == tlx || x == brx || y == tly || y == bry) return true;
    return false;
}

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int q;
    cin >> q;
    int n, *x, *y;
    int maxx, minx, maxy, miny;
    bool isValid;
    for (int q_i = 0; q_i < q; q_i++) {
        cin >> n;
        x = new int[n];
        y = new int[n];
        maxx = maxy = -1e4 + 1;
        minx = miny = 1e4 - 1;
        for (int i = 0; i < n; i++) {
            cin >> x[i] >> y[i];
            maxx = max(x[i], maxx);
            minx = min(x[i], minx);
            maxy = max(y[i], maxy);
            miny = min(y[i], miny);
        }
        isValid = true;
        for (int i = 0; i < n; i++)
            if (!checkRectangle(x[i], y[i], minx, miny, maxx, maxy)) isValid = false;
        cout << (isValid ? "YES" : "NO") << endl;
    }
        
    return 0;
}