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

int inf = 1000000;

void updateMin(int val,  int& minVal) {
    if (val < minVal)
        minVal = val;
}

void updateMax(int val,  int& maxVal) {
    if (val > maxVal)
         maxVal = val;
}

bool onEdge(int x, int y, int minX, int maxX, int minY, int maxY) {
    //cerr << x << ' ' << y << ' ' << minX << ' ' << maxX << ' ' << minY << ' ' << maxY << endl;
    return x == minX || x == maxX || y == minY || y == maxY;
}
bool testCase() {
    int n; cin >> n;
    vector<int> x(n), y(n);
    int minX = inf, minY = inf, maxX = -inf, maxY = -inf;
    for (int i = 0; i < n; ++i) {
        cin >> x[i] >> y[i];
        updateMin(x[i], minX);
        updateMax(x[i], maxX);
        updateMin(y[i], minY);
        updateMax(y[i], maxY);
    }
    //if (minX == maxX || minY == maxY)
    //    return false;
    for (int i = 0; i < n; ++i)
        if (!onEdge(x[i], y[i], minX, maxX, minY, maxY))
            return false;
    return true;
}

int main() {
    int q; cin >> q;
    while (q--)  {
        if (testCase())
            cout << "YES" << endl;
        else
            cout << "NO" << endl;
    }
}