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

typedef pair<int, int> pii;

#define fs first
#define sc second

int main() {
    int q;
    scanf("%d", &q);
    while (q--) {
        int n;
        scanf("%d", &n);
        vector<pii> p(n);
        for (int i = 0; i < n; ++i) 
            scanf("%d %d", &p[i].fs, &p[i].sc);
        int maxx = p[0].fs, minx = p[0].fs, maxy = p[0].sc, miny = p[0].sc;
        for (int i = 1; i < n; ++i) {
            maxx = max(p[i].fs, maxx);
            minx = min(p[i].fs, minx);
            maxy = max(p[i].sc, maxy);
            miny = min(p[i].sc, miny);
        }
        bool found = true;
        for (int i = 0; i < n; ++i)
            if (p[i].fs != maxx && p[i].fs != minx && p[i].sc != maxy && p[i].sc != miny) {
            found = false;
            break;
        }
        puts(found ? "YES" : "NO");
    }
    return 0;
}