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


int main() {
    int q,n;
    cin>>q;
    while(q--) {
        cin>>n;
        vector<pair<long, long> > arr(n);
        set<long> x,y;
        for(int i=0;i<n;i++){
            cin>>arr[i].first>>arr[i].second;
            x.insert(arr[i].first);
            y.insert(arr[i].second);
        }
        bool flag = false;
        set<long>::iterator xi,xj,yi,yj;
        if(x.size()==1 || y.size()==1)
            flag = true;
        for(xi=x.begin();xi!=x.end();xi++){
            for(xj = next(xi);xj!=x.end();xj++) {
                for(yi = y.begin();yi!=y.end();yi++){
                    for(yj = next(yi) ;yj!=y.end();yj++) {
                        int i;
                        for(i=0;i<arr.size();i++) {
                            if(((arr[i].first==*xi || arr[i].first==*xj) && (arr[i].second <= max(*yi,*yj) && arr[i].second >= min(*yi,*yj))) || ((arr[i].second==*yi || arr[i].second==*yj) && (arr[i].first>=min(*xi,*xj) && arr[i].first <= max(*xi,*xj))))
                                continue;
                            break;
                        }
                        if(i==arr.size())
                            flag = true;
                    }
                }
            }
        }
        if(flag) {
            cout<<"YES"<<endl;
        } else {
            cout<<"NO"<<endl;
        }
    }
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    return 0;
}