#include <bits/stdc++.h>
#define pb push_back
using namespace std;
typedef long long LL;
const int S = 100003;
const int MOD = 1e9+7;
const double pi = 2 * acos (0.0);
int _In(){int x; scanf("%d", &x); return x;}
LL _LLI(){LL x; scanf("%lf", &x); return x;}
int dirX[]={1, 0, -1, 0, 1, -1, 1, -1};
int dirY[]={0, 1, 0, -1, 1, -1, -1, 1};
int rX[] = {1, 1, 2, 2, -1, -1, -2, -2};
int rY[] = {2, -2, 1, -1, 2, -2, 1, -1};

template <class T> T Distance(T x1, T y1, T x2, T y2){return sqrt((x1-x2)*(x1-x2)+(y1-y2)*(y1-y2));};

int sset(int N, int pos){return N=N|(1<<pos);}
bool check(int N, int pos){return (bool)(N&(1<<pos));}
int reset(int N, int pos){return N=N&~(1<<pos);}
///...............Code Starts From Here...............///

double x[S], y[S];

int main(){
    int q = _In();
    while(q--){
        int n = _In();
        for(int i = 0; i < n; i++){
            x[i] = _In();
            y[i] = _In();
        }
        int f = 0;
        for(int i = 0; i < n; i++){
            for(int j = i+1; j < n; j++){
                for(int k = j+1; k < n; k++){
                    if(Distance(x[i], y[i], x[j], y[j]) == Distance(x[i], y[i], x[k], y[k])+Distance(x[k], y[k], x[j], y[j])){
                        f = 1;
                        break;
                    }
                    if(Distance(x[i], y[i], x[k], y[k]) == Distance(x[i], y[i], x[j], y[j])+Distance(x[k], y[k], x[j], y[j])){
                        f = 1;
                        break;
                    }
                    if(Distance(x[k], y[k], x[j], y[j]) == Distance(x[i], y[i], x[k], y[k])+Distance(x[i], y[i], x[j], y[j])){
                        f = 1;
                        break;
                    }
                }
                if(f)break;
            }
            if(f)break;
        }
        if(!f)cout << "YES" << endl;
        else puts("NO");
    }
    return 0;
}