#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <bits/stdc++.h>
using namespace std;
const double EPS = 0.0000000001;
int x[11], y[11];

inline long double dist (int f, int s) {
    return sqrt ((x[f] - x[s]) * (x[f] - x[s]) + (y[f] - y[s]) * (y[f] - y[s]));
}

int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    
    int q;
    
    cin >> q;
    
    for (int it=1; it<=q; ++it) {
        int n;
        bool Good = 1;
        cin >> n;
        for (int i=1; i<=n; ++i) {
            cin >> x[i] >> y[i];
        }
        
        for (int i=1; i<=n; ++i) {
            for (int j=1; j<=n; ++j) {
                if (i == j)
                    continue;
                for (int k=1; k<=n; ++k) {
                    if (k == j || k == i)
                        continue;
                    if (abs (dist (i, j) + dist (i, k) - dist (j, k)) < EPS)
                        Good = 0;
                }
            }
        }
        
        if (Good)
            puts ("YES");
        else
            puts ("NO");
        
    }
    
    
    
    return 0;
}