#include <bits/stdc++.h>
using namespace std;
set <long long int> s;
long long int n,q,a,b;
int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */  
    bool flag;
    cin>>q;
    while(q--)
        {
        cin>>n;
        flag=0;
        cin>>a>>b;
        s.insert(a);
        s.insert(b);
        
        cin>>a>>b;
        if(s.size()>=2 && s.find(a)==s.end())
        { cout<<"NO\n";
          continue;
        }
        else s.insert(a);
        if(s.size()>=2 && s.find(b)==s.end())
        { cout<<"NO\n";
          continue;
        }
        else s.insert(b);
        
        n-=2;
        while(n--)
        {
            cin>>a>>b;
            if(s.size()>=2 && s.find(a)==s.end())
             { 
             flag=1;
              break;
              }
            if(s.size()>=2 && s.find(b)==s.end())
            { 
              flag=1;
              break;
             }
        }
        if(flag)
        cout<<"NO\n";
        else
        cout<<"YES\n";
    }
    return 0;
}