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


int main() {
    ios_base::sync_with_stdio(false);
    int t;
    cin>>t;
    while(t--)
        {
        int n,ele,i,flag=0;
        cin>>n;
        vector<int>x,y;
        set<int>s1,s2;
        for(i=0;i<n;i++)
            {
            cin>>ele;
            x.push_back(ele);
            if(ele!=0)
            s1.insert(ele);
            cin>>ele;
            y.push_back(ele);
            if(ele!=0)
            s2.insert(ele);
        }
        if(s1.size()==1 && s2.size()==1)
            flag=1;
        if(flag==1)
            cout<<"YES"<<endl;
        else
            cout<<"NO"<<endl;
        x.clear();
        y.clear();
        s1.clear();
        s2.clear();
    }
    return 0;
}