#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 t,n,a,b,c=0,x;
    cin>>t;
    while(t--)
        {
        cin>>n;
        x=n;
        while(n--)
            {
            cin>>a>>b;
            if(a==0||b==0)
                {
                c++;
            }
        }
        if(c==x)
            cout<<"YES"<<endl;
        else
            cout<<"NO"<<endl;
        c=0;
    }
    return 0;
}