#include <bits/stdc++.h>
using namespace std;
#define aa long long
int main()
{
    ios_base::sync_with_stdio(false);
    aa int tc;
    cin>>tc;
    while(tc--)
    {
        aa int q,coun=0;
        cin>>q;
        int yo = q;
        while(q--)
        {
            aa int a,b;
           // coun=0;
            cin>>a>>b;
            if(a==0 || b==0)
            {
                coun++;
            }
        }
        if(coun == yo) cout<<"YES"<<endl; else cout<<"NO"<<endl;
    }
}