#include <bits/stdc++.h>
using namespace std;

#define xx first
#define yy second
typedef pair<int, int> ii;

int main() {
    int t; cin >> t;
    while (t--) {
        int n; cin >> n;
        vector<ii> a(n);
        for (int i = 0; i < n; ++i) cin >> a[i].xx >> a[i].yy;
        ii tl(INT_MAX, INT_MAX);
        ii br(INT_MIN, INT_MIN);
        for (int i = 0; i < n; ++i) {
            tl.xx = min(tl.xx, a[i].xx);
            tl.yy = min(tl.yy, a[i].yy);
            br.xx = max(br.xx, a[i].xx);
            br.yy = max(br.yy, a[i].yy);
        }
        
        bool ans = true;
        for (int i = 0; i < n; ++i) {
            if (a[i].xx == tl.xx or a[i].xx == br.xx) continue;
            if (a[i].yy == tl.yy or a[i].yy == br.yy) continue;
            ans = false;
            break;
        }
        cout << (ans ? "YES" : "NO") << '\n';
    }
    return 0;
}