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


int main() {
    /* Enter your code here. Read input from STDIN. Print output to STDOUT */   
    int q;
    cin >> q;
    while(--q>=0) {
        int n;
        cin >> n;
        vector<pair<int,int>> v(n);
        for(int i=0;i<n;++i) {
            int x,y;
            cin >> y>>x;
            v[i]=make_pair(y,x);
        }
        
        int maxx=-1000000;
        int maxy=-1000000;
        int minx=1000000;
        int miny=1000000;

        for(int i=0;i<n;++i) {
            maxx = max(maxx, v[i].second);
            minx = min(minx, v[i].second);
            maxy = max(maxy, v[i].first);
            miny = min(miny, v[i].first);
        }
        
        bool ok=true;
        for(int i=0;i<n;++i) {
            if(v[i].first == miny || v[i].first==maxy || v[i].second==maxx || v[i].second==minx) {
                
            } else {
                ok=false;
                break;
            }
        }
        if(ok)
            cout << "YES"<<endl;
        else 
            cout <<"NO"<<endl;
        
    }
    return 0;
}