#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <bits/stdc++.h>
using namespace std;


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */ 
    int q;
    cin>>q;
    int n;
    while(q--)
    {
        
        cin>>n;
        int x[n],y[n];
        set<int> s1,s2;
        for(int i=0;i<n;i++)
            {
            cin>>x[i]>>y[i];
            s1.insert(x[i]);
            s2.insert(y[i]);
        }
        int f=0;
        if(s1.size()<=2 && s2.size()<=2 && (s1.size() == s2.size()))
            {
            auto i=s1.begin();
            auto j=s2.begin();
            for(;i!=s1.end();i++,j++)
                {
                if((*i) != (*j))
                    {
                    f=1;
                    break;
                }
            }
        }
        else
            {
            f=1;
        }
        if(f==0)
            {
            cout<<"YES\n";
        }
        else
            {
            cout<<"NO\n";
        }
    }
    return 0;
}