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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int q;
    int counter=0,n;
    unsigned long long int temp1,temp2;
    cin>>q;
    while(q--)
        {
        cin>>n;
        int arr[n][2];
        for(int i=0;i<n;i++)
            {
                    cin>>temp1>>temp2;
                    arr[i][0]=temp1;
                    arr[i][1]=temp2;
            }
        for(int i=0;i<n;i++)
            {
                    if(arr[i][0]==0 || arr[i][1]==0)
                        {}
                    else
                        ++counter;
        }
        if(counter==0)
            cout<<"YES"<<endl;
        else
            cout<<"NO"<<endl;
    }
    return 0;
}