#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#define INF 10000000
using namespace std;

int main() {
    int q,n;
    cin >> q;
    while(q--) {
        cin >> n;
        int x[n], y[n], x1 = INF, x2 = INF, y1 = INF, y2 = INF, flag = 1;
        for(int i=0;i<n;i++)
            cin >> x[i] >> y[i];
        int top = -INF, bottom = INF, left = INF, right = -INF;
        for(int i=0;i<n;i++) {
            if(x[i] > right)
                right = x[i];
            if(x[i] < left)
                left = x[i];
            if(y[i] > top)
                top = y[i];
            if(x[i] < bottom)
                bottom = y[i];
        }
        if(left == INF)
            left *= -1;
        if(right == -INF)
            right *= -1;
        if(top == -INF)
            top *= -1;
        if(bottom == INF)
            bottom *= -1;
     //   cout << top << " " << bottom << " " << left << " " << right << "\n";
        for(int i=0;i<n;i++) {
            if((x[i] == left || x[i] == right) && (y[i] <= top && y[i] >= bottom))
                continue;
            else if ((y[i] == top || y[i] == bottom) && (x[i] <= right && x[i] >= left))
                continue;
            else {
                flag = 0;
                break;
            }
        }
            if(flag)
                cout << "YES\n";
            else
                cout << "NO\n";
    }
    return 0;
}