#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#define EPS 0.0000001
using namespace std;
double Abs(double g)
    {
    if(g<0)
        return -g;
    return g;
    
}
void solve()
    {
    
    int n, x, y, ans;
    vector <double> v;
    cin>>n;
    for(int i=1;i<=n;i++)
        {
    cin>>x>>y;
    v.push_back(1.*x/y);
    }
    sort(v.begin(), v.end());
    for(int i=1;i<v.size();i++)
        {
        if(Abs(v[i]-v[i-1])>EPS)
           ans++;
    }
           if(ans==3)
           cout<<"YES\n";
           else cout<<"NO\n";
}


int main() {
    int n;
cin>>n;
    
    while(n)
        {
        solve();
        n--;
        
    }
    
    return 0;
}