#include <bits/stdc++.h>
#define ll long long int

using namespace std;

int arrX[15],arrY[15];

int main(){
    int q;

    cin>>q;

    for(int query=1;query<=q;query++){
        int n;
        cin>>n;

        int leftMost,rightMost,upMost,downMost;


        int x,y;
        cin>>x>>y;
        arrX[0]=x; arrY[0]=y;
        leftMost=x; rightMost=x; upMost=y; downMost=y;

        for(int i=1;i<n;i++){
            cin>>arrX[i]>>arrY[i];
            leftMost=min(leftMost,arrX[i]);
            rightMost=max(rightMost,arrX[i]);
            upMost=max(upMost,arrY[i]);
            downMost=min(downMost,arrY[i]);
        }

        bool ok=true;

        for(int i=0;i<n;i++){
            if (arrX[i]==leftMost || arrX[i]==rightMost){
                if (!(arrY[i]<=upMost && arrY[i]>=downMost )){
                    ok=false;
                    break;
                }
            }
            else if (arrY[i]==upMost || arrY[i]==downMost){
                if (!(arrX[i]>=leftMost && arrX[i]<=rightMost)){
                    ok=false;
                    break;
                }
            }
            else {
                ok=false;
                break;
            }
        }

        if (ok)
            cout<<"YES"<<endl;
        else cout<<"NO"<<endl;


    }

}