//By Don4ick
#include <bits/stdc++.h>

const int N = 11;
using namespace std;
int q, n;
long long x[N], y[N];

bool check(int a, int b, int c)
{
	return (((x[b] - x[a]) * (y[c] - y[a])) - ((x[c] - x[a]) * (y[b] - y[a])) != 0);
}	

int main()
{
	scanf("%d", &q);
	
	while(q--)
	{
		scanf("%d", &n);
		
		for (int i = 0; i < n; i++)
			scanf("%d%d", &x[i], &y[i]);
			
		bool ans = true;
		for (int i = 0; i < n; i++)
			for (int j = i + 1; j < n; j++)
				for (int k = j + 1; k < n; k++)
					ans &= check(i, j, k);
		for (int i = 0; i < n; i++)
		{
			for (int j = i + 1; j < n; j++)
			{
				for (int k = j + 1; k < n; k++)
				{
					ans &= ((x[i] - x[j] == 0) || (y[i] - y[j] == 0) 
								|| (x[k] - x[j] == 0) || (y[k] - y[j] == 0)
								|| (x[k] - x[i] == 0) || (y[k] - y[i] == 0));
				}
			}
		}
		if (ans)
			printf("YES\n");
		else
			printf("NO\n");	
	}

	return 0;
}