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

const int C = (int)1e5;
const int N = 20;
int n;
int a[N][2];
int x[N], y[N];

bool solve()
    {
    scanf("%d", &n);
    for (int i = 0; i < n; i++)
        {
        scanf("%d%d", &a[i][0], &a[i][1]);
        x[i] = a[i][0];
        y[i] = a[i][1];
    }
    x[n] = y[n] = -C;
    x[n + 1] = y[n + 1] = C;
    sort(x, x + n + 2);
    sort(y, y + n + 2);
    int xSz = unique(x, x + n + 2) - x;
    int ySz = unique(y, y + n + 2) - y;
    for (int i = 0; i < xSz; i++)
        for (int j = i + 1; j < xSz; j++)
            for (int k = 0; k < ySz; k++)
                for (int h = k + 1; h < ySz; h++)
                {
                    bool ok = true;
                    for (int it = 0; it < n; it++)
                    {
                        ok &= x[i] <= a[it][0] && a[it][0] <= x[j] && y[k] <= a[it][1] && a[it][1] <= y[h];
                        ok &= (a[it][0] == x[i] || a[it][0] == x[j] || a[it][1] == y[k] || a[it][1] == y[h]);
                    }
                    if (ok) return true;
    }
    return false;
}

int main() {
    
    int t;
    scanf("%d", &t);
    while(t--)
        {
        if (solve())
            printf("YES\n");
        else
            printf("NO\n");
    }
    
    return 0;
}