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


int main() {
    int q,n,x,y;

    cin>>q;
    while(q--)
    {
        cin>>n;
        int flag=1;
        while(n--)
        {
            cin>>x>>y;

            if(x!=0 && y!=0)
            {
                flag=0;
            }
        }
        if(flag==0)
            cout<<"NO\n";
        else
            cout<<"YES\n";
    }
    return 0;
}