#include <bits/stdc++.h>
using namespace std;


int main() {
    int q;
    cin>>q;
    
        vector<pair<int,int> > v;
    int n=0;
    while(q--)
    {
        int nn;
        cin>>nn;
        for(int i=0;i<nn;i++)
        {
            int a,b;
            cin>>a>>b;
            v.push_back(make_pair(a,b));
        }
        int f=0;
        n+=nn;
     //   cout<<n<<endl;
        for(int i=0;i<n;i++)
        {
            for(int j=i+1;j<n;j++)
            {
                double y=v[j].second-v[i].second;
                double x=v[j].first-v[i].first;
                double s1=1;
                if(x!=0) s1=y/x;
               // cout<<s1<<endl;
                for(int k=j+1;k<n;k++)
                {
                    double yy=v[j].second-v[k].second;
                
                    double xx=v[j].first-v[k].first;
                    double s2=1;
                    if(xx!=0)
                        s2=yy/xx;
                   // cout<<s2<<endl;
                    
                    else if(s1==s2) continue;
                    else if((s1*s2)==-1) continue;
                    else
                    {
                        f=1;
                        break;
                    }
                   // cout<<i<<" "<<j<<" "<<k<<" || "<<s1<<" "<<s2<<endl;
                }
                if(f==1) break;
            }
            if(f==1) break;
        }
        if(f==1) cout<<"NO"<<endl;
        else cout<<"YES"<<endl;
    }
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}