#include <iostream>
#include <vector>
#include <map>
using namespace std;
int n;
vector<int> x;
vector<int> y;
int main()
{
    int q;
    cin >> q;
    for (int uu=0; uu<q; uu++)
    {

        cin >> n;
        for (int i=0;i<n;i++)
        {
            int x2,y2;
            cin >> x2 >> y2;
            x.push_back(x2);
            y.push_back(y2);
        }
        for (int i=0;i<n;i++)
        {
            for (int j=0;j<n;j++)
            {
                for (int k=0;k<n;k++)
                {
                    if (x[i]<x[j]&&x[j]<x[k]&&y[i]<y[j]&&y[j]<y[k]){cout << "NO" << endl;goto nahui;}
                    if (x[i]>x[j]&&x[j]>x[k]&&y[i]<y[j]&&y[j]<y[k]){cout << "NO" << endl;goto nahui;}
                    if (x[i]<x[j]&&x[j]<x[k]&&y[i]>y[j]&&y[j]>y[k]){cout << "NO" << endl;goto nahui;}
                    if (x[i]>x[j]&&x[j]>x[k]&&y[i]>y[j]&&y[j]>y[k]){cout << "NO" << endl;goto nahui;}
                }
            }
        }
        cout << "YES" << endl;
        nahui:
        x.clear();
        y.clear();
    }
    return 0;
}