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


int main() {
    int q, n;
    set <int> xi, yi;
    cin >> q;
    while(q--) {
        cin >> n;
        int minx = 100000, miny = 100000, maxx = -100000, maxy = -100000;
        int x[n], y[n];
        for(int i = 0; i < n; i++) {
            cin >> x[i] >> y[i];
            minx = min(minx, x[i]);
            maxx = max(maxx, x[i]);
            miny = min(miny, y[i]);
            maxy = max(maxy, y[i]);
        
        }
        int flag = 1;
        for(int i = 0; i < n; i++) {
            if(x[i] == minx) {
                if(y[i] >= miny && y[i] <= maxy)
                    ;
                else {
                    flag = 0;
                    break;
                }
            }
            else if(x[i] == maxx) {
                if(y[i] >= miny && y[i] <= maxy)
                    ;
                else {
                    flag = 0;
                    break;
                }
            }
            else if(y[i] == miny) {
                if(x[i] >= minx && x[i] <= maxx)
                    ;
                else {
                    flag = 0;
                    break;
                }
            }
            else if(y[i] == maxy) {
                if(x[i] >= minx && x[i] <= maxx)
                    ;
                else {
                    flag = 0;
                    break;
                }
            }
            else {
                flag = 0;
                break;
            }
            
        }
        if(flag)
            cout << "YES\n";
        else
            cout << "NO\n";

        
    }
    return 0;
}