#include <bits/stdc++.h>
using namespace std;
#define mod 1000000007
#define N 1000001
#define hg ios_base::sync_with_stdio(0);cin.tie(0)
#define ff first
#define ss second
#define gcd __gcd
#define inf (1<<30)
#define pb push_back
#define mp make_pair
#define pii pair<int,int>
#define all(xx) xx.begin(),xx.end()
#define bitcit __builtin_popcount
#define mset(x,y) memset(x,y,sizeof(x))
#define INF 1e18
#define ll long long
#define endl "\n"

ll minn(ll a,ll b)
{
	if(a!=0&&a<=b)
	return a;
	return b;
}
int slope(ll x1,ll y1,ll x2,ll y2)
{
	int ss=(y2-y1);
	int xx=(x2-x1);
	if(xx==0)
	return 90;
	return ss/xx;
}
pair<ll,ll> p[N];
map< pair<ll,ll> ,int> mark;
int main() {
    hg;
    int t;
    cin>>t;
    while(t--)
    {  
    	int n,i,j;
    	cin>>n;
    	mark.clear();
    	int f=1;
    	for(i=0;i<n;i++)
    	cin>>p[i].ff>>p[i].ss;
    	
    	for(i=0;i<n;i++)
    	{
    		//if(mark[mp(p[i].ff,p[i].ss)]==0)
    	//	{
    			//mark[mp(p[i].ff,p[i].ss)]=1;
    			for(j=0;j<n;j++)
    			{
    				if(i!=j){
    					if(mark[mp(p[j].ff,p[j].ss)]==0)
    					{
    					int m=slope(p[i].ff,p[i].ss,p[j].ff,p[j].ss);
    					if(m==0)
    					mark[mp(p[j].ff,p[j].ss)]=1;
    					}
    				}
    			}
    	//	}
    	}
    	for(i=0;i<n;i++)
    	{
    		if(mark[{p[i].ff,p[i].ss}]!=1)
    		{
    			f=0;
    		}
    	}
    	if(!f)
    	cout<<"NO\n";
    	else
    	cout<<"YES\n";
    }
	return 0;
}