#include <cmath>
#include <cstdio>
#include <climits>
#include <vector>
#include <iostream>
#include <algorithm>
#include <utility>

using namespace std;

typedef pair<int, int> pii;

bool f(const vector<pii>& points) {
    int minX = INT_MAX;
    int maxX = INT_MIN;
    int minY = INT_MAX;
    int maxY = INT_MIN;
    for (auto& p : points) {
        minX = min(minX, p.first);
        maxX = max(maxX, p.first);
        minY = min(minY, p.second);
        maxY = max(maxY, p.second);
    }
    
    // cout << minX << " " << maxX << " " << minY << " " << maxY << endl;
    for (auto& p : points) {
        if (p.first > minX && p.first < maxX) {
            if (p.second != minY && p.second != maxY) {
                return false;
            }
        } else {
            if (p.second < minY || p.second > maxY) {
                return false;
            }
        }
    }
    return true;
}

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    int q;
    cin >> q;
    for (int q_ = 0; q_ < q; ++q_) {
        int n;
        cin >> n;
        vector<pii> points(n);
        for (int i = 0; i < n; ++i) {
            cin >> points[i].first >> points[i].second;
        }
        cout << (f(points) ? "YES" : "NO");
        cout << endl;
    }
    return 0;
}