#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;
    cin>>q;
    while(q--){
        int n;
        cin>>n;
        int a ,b;
        int flag =0;
        for(int i= 0;i<n;i++)
            {
            cin>>a>>b;
            if(a && b)
                {
                flag =1;
            }
        }
        
        if(flag)
            {
            cout<<"NO"<<endl;
        }
        else
            {
            cout<<"YES"<<endl;
        }
    }
    return 0;
}