#include<bits/stdc++.h>
using namespace std;
int q, n, a, b, c, d, i, x[15], y[15];

int main()
{

        scanf("%d", &q);
        while(q--){
            a = INT_MAX;
            b = INT_MAX;
            c = INT_MIN;
            d = INT_MIN;
            scanf("%d", &n);
        for(i=0;i<n;i++){
            scanf("%d%d", &x[i], &y[i]);
            if(a > x[i])
                a = x[i];
            if(b > y[i])
                b = y[i];
            if(c<x[i])
                c = x[i];
            if(d < y[i])
                d = y[i];
        }
        for(i=0;i<n;i++){
            if(x[i]!=a && x[i]!=c && y[i]!=b && y[i]!=d)
                break;
        }
        if(i<n)
        printf("NO\n");
        else printf("YES\n");

        }
    return 0;
}