import java.io.*;
import java.util.*;

public class Solution {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int q = in.nextInt();
        for (int i = 0; i < q; ++i) {
            solve(in);
        }
    }
    
    private static void solve(Scanner in) {
        int n = in.nextInt();
        int[] x = new int[n];
        int[] y = new int[n];
        final int INF = 100000;
        int lx = INF;
        int ly = INF;
        int rx = -INF;
        int ry = -INF;
        for (int i = 0; i < n; ++i) {
            x[i] = in.nextInt();
            y[i] = in.nextInt();
            lx = Math.min(lx, x[i]);
            ly = Math.min(ly, y[i]);
            rx = Math.max(rx, x[i]);
            ry = Math.max(ry, y[i]);
        }
        
        
        boolean ok = true;
        for (int i = 0; i < n; ++i) {
            if (x[i] == lx || x[i] == rx) {
                ok &= (ly <= y[i] && y[i] <= ry);
            } else {
                ok &= (y[i] == ly || y[i] == ry);
                ok &= (lx <= x[i] && x[i] <= rx);
            }
        }
        System.out.println(ok ? "YES" : "NO");
    }
}