#include<iostream>
#include<algorithm>
#include<cstdio>
#include<cstring>

using namespace std;

#define N 25

int n;

struct node
{
    int x, y;
}P[N];

int slove(int i, int j, int k, int q)   // 判断是否为正四边形
{
    if(i == j || i == k)   // 不能有重点
        return false;
    if(i == q || j == k)
        return false;
    if(j == q || k == q)
        return false;

    int w = 0, num[8];
    memset(num, 0, sizeof(num));

    num[w++] = (P[i].x-P[j].x)*(P[i].x-P[j].x)+(P[i].y-P[j].y)*(P[i].y-P[j].y);
    num[w++] = (P[i].x-P[k].x)*(P[i].x-P[k].x)+(P[i].y-P[k].y)*(P[i].y-P[k].y);
    num[w++] = (P[i].x-P[q].x)*(P[i].x-P[q].x)+(P[i].y-P[q].y)*(P[i].y-P[q].y);
    num[w++] = (P[j].x-P[k].x)*(P[j].x-P[k].x)+(P[j].y-P[k].y)*(P[j].y-P[k].y);
    num[w++] = (P[j].x-P[q].x)*(P[j].x-P[q].x)+(P[j].y-P[q].y)*(P[j].y-P[q].y);
    num[w++] = (P[q].x-P[k].x)*(P[q].x-P[k].x)+(P[q].y-P[k].y)*(P[q].y-P[k].y);

    sort(num, num+w);

    w = unique(num, num+w) - num;

    if(w != 2)     // 只能有两种不相同的边
        return false;
    return true;
}

int main()
{
    int t;
    scanf("%d\n", &t);
    while(t--)
    {
        scanf("%d", &n);

        int ans = 0;

        for(int i = 1; i <= n; i++)
            scanf("%d%d", &P[i].x, &P[i].y);
        if(n != 4)
        {
            printf("NO\n");
            continue;
        }

        for(int i = 1; i <= n; i++)
            for(int j = i+1; j <= n; j++)
                for(int k = j+1; k <= n; k++)
                    for(int q = k+1; q <= n; q++)
                        if(slove(i, j, k, q))
                            ans++;
        if(ans != 0)
            printf("YES\n");
        else
            printf("NO\n");
    }
    return 0;
}