#include <iostream>

using namespace std;

struct dot {
    int x, y;
    dot () {}
    dot (int _x,  int _y) {x = _x; y = _y;}
};

dot all[20];

bool check(int a, int b) {
    if (all[a].x == all[b].x) return true;
    if (all[a].y == all[b].y) return true;
    return false;
}

int main() {
    int a,b,c,d;
    cin >> a;
    for (int i = 0; i < a; ++i) {
        cin >> b;
        for (int i2 = 0; i2 < b; ++i2) {
            cin >> c >> d;
            all[i2] = dot(c,d);
        }

        bool pass = true;

        int xMax = -9999999, xMin = 9999999, yMax = -9999999, yMin = 9999999;

        for (int i2 = 0; i2 < b; ++i2) {
            if (all[i2].x > xMax) xMax = all[i2].x;
            if (all[i2].x < xMin) xMin = all[i2].x;
            if (all[i2].y > yMax) yMax = all[i2].y;
            if (all[i2].y < yMin) yMin = all[i2].y;
        }

        all[b] = dot(xMax, yMax);
        all[b+1] = dot(xMin, yMin);
        //cout << xMax << " " << yMax << "   :   " << xMin << " " << yMin << endl;
        if (b > 1) {
            for (int i2 = 0; i2 < b; ++i2) {
                if (!check(i2, b) && !check(i2, b+1)) {
                    pass = false; break;
                }
            }
        }

        if (pass) cout << "YES" << endl;
        else cout << "NO" << endl;
    }

    return 0;
}