//An Emperor Production
//in Association with Assistant Professor MR Ram Kripal Mishra.
//Copyright (C) 2016,2015 CodeGeeks, Inc.,
//B-217 KIT, First Floor, Rooma, Kanpur, INDIA
//Everyone is permitted to copy and distribute verbatim copies
//of this code, but changing it is not allowed.
#include<bits/stdc++.h>
using namespace std;
#define ln pf("\n")
#define sp pf(" ")
#define loop(a,b) for(int i=a;i<b;i++)
#define rloop(a,b) for(int i=a;i>=b;i--)
#define pb push_back
#define ppb pop_back()
#define pf printf
#define pi pair<int,int>
#define sf scanf
#define swi switch
#define vec vector
#define veci vector<int>
#define vecs vector<string>
#define boost1 ios::sync_with_stdio(false);
#define boost2 cin.tie(0);
#define MOD 1000000007
typedef long long ll;
typedef string str;
void ins(string &s){getline(cin,s);}
double power(ll x, ll y){double temp;if( y == 0)return 1;temp = power(x, y/2);if (y%2 == 0)return temp*temp;else{if(y > 0)return x*temp*temp;else return (temp*temp)/x;}}
str to_binary(ll n){str S;if(n==1)return "1";else{S+=to_binary(n>>1);S+=(n%2+'0');}return S;}
void in(int &V){cin>>V;}
void in(ll &V){cin>>V;}
int inr(){int V;cin>>V;return V;}
void in(char &V){cin>>V;}
void in(string &V){cin>>V;}
void out(int V){cout<<V;}
void out(double V){cout<<V;}
void out(ll V){cout<<V;}
void out(char V){cout<<V;}
void out(string V){cout<<V;}


int main()
{
   
    int t;
    in(t);
    while(t--)
        {
        int n,m;
        int test;
        int flag=1;
        in(test);
        while(test--)
            {
        cin>>n>>m;
        
            if(n&&m)
                flag=0;
            if(flag==0)
                {
                break;
            }
            
        }
        if(flag)cout<<"YES";
        else 
            cout<<"NO";
        ln;
        
    }
    return 0;
}