#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <set>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */
    int n , q ,a,b;
    set<int> x,y;
    cin >> q;
    while(q--)
        {
        cin >> n;
        while(n--)
            {
            cin >> a >> b;
            x.insert(a);
            y.insert(b);
        }
        if(x.size() > 2 && y.size() > 2)
            {
            cout << "NO\n";
            x.clear();
            y.clear();
            continue;
        }
        else
            {
            cout << "YES\n";
            x.clear();
            y.clear();
        }
    }
        
    
    return 0;
}