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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int q,n,x,y;
    cin>>q;
    while(q--){
        int flag=0;
        cin>>n;
        cin>>x>>y;
        int temp_x,temp_y;temp_x=x,temp_y=y;n-=1;
        while(n--){
            cin>>x>>y;
            if((x!=temp_x||y!=temp_y)&&(x!=0&&y!=0))flag=1;
        }
    if(flag)cout<<"NO\n";
        else cout<<"YES\n";
    }
    return 0;
}