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

bool Check(int a[],int b[],int n){
   // cout << "111";
    vector <pair <int, int > > lat0,lat1,lat2,lat3;
    lat0.push_back(make_pair(a[1],b[1]));
    a[1] = 11111;
    b[1] = 11111;
    for(int i=2;i<=n;i++)
       if(a[i] == lat0[0].first && a[i] != 11111){
            lat0.push_back(make_pair(a[i],b[i]));
            a[i] = 11111;
            b[i] = 11111;
        }
    //
    for(int i=1;i<=n;i++)
           if(a[i] != 11111){
            lat1.push_back(make_pair(a[i],b[i]));
            a[i] = 11111;
            b[i] = 11111;
            break;
    }
    if(lat1.size() > 0)
    for(int i=2;i<=n;i++)
       if(a[i] == lat1[0].first && a[i] != 11111){
            lat1.push_back(make_pair(a[i],b[i]));
            a[i] = 11111;
            b[i] = 11111;
        }
    //
    for(int i=1;i<=n;i++)
           if(a[i] != 11111){
            lat2.push_back(make_pair(a[i],b[i]));
            a[i] = 11111;
            b[i] = 11111;
            break;
    }
    //cout << 1;
    if(lat2.size() > 0)
    for(int i=2;i<=n;i++)
       if(a[i] == lat2[0].first && a[i] != 11111){
            lat2.push_back(make_pair(a[i],b[i]));
            a[i] = 11111;
            b[i] = 11111;
       }
     for(int i=1;i<=n;i++)
           if(a[i] != 11111){
            lat3.push_back(make_pair(a[i],b[i]));
            a[i] = 11111;
            b[i] = 11111;
            break;
    }
    if(lat3.size() > 0)
    for(int i=2;i<=n;i++)
       if(a[i] == lat3[0].first && a[i] != 11111){
            lat3.push_back(make_pair(a[i],b[i]));
            a[i] = 11111;
            b[i] = 11111;
       } 
    //cout << 1;
   /* for(int i=0;i<lat0.size();i++)
            cout << lat0[i].first << ' ' << lat0[i].second << endl;
    cout << endl;
    for(int i=0;i<lat1.size();i++)
            cout << lat1[i].first << ' ' << lat1[i].second << endl;
    cout << endl;
    for(int i=0;i<lat2.size();i++)
            cout << lat2[i].first << ' ' << lat2[i].second << endl;
    cout << endl;
    for(int i=0;i<lat3.size();i++)
            cout << lat3[i].first << ' ' << lat3[i].second << endl;
    */
    if(lat0.size() > 0 && lat1.size() > 0 && lat2.size() > 0  && lat3.size() > 0)
    return(1);
    return(0);
}


int main() {
    int q;
    cin >> q;
    for(int t=1;t<=q;t++){
            int a[20],b[20];
            int n;
            cin >> n;
            for(int i=1;i<=n;i++)
                    cin >> a[i] >> b[i];
            if(Check(a,b,n))
                       cout << "YES" << endl;
            else
                       cout << "NO" << endl;
    }
    return 0;
}