#include <iostream>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#include <cstring>
#include <climits>
#include <algorithm>
#include <numeric>
#include <string>
#include <vector>
#include <map>
#include <unordered_map>
#include <queue>
#define x first
#define y second

using namespace std;

typedef long long int64;
typedef pair<int, int> intp;

int T, n;
vector<intp> a;

bool validate(intp a, intp b, intp c) {
    bool dx = (b.x > a.x && b.x < c.x);
    if (a.y > c.y)
        swap(a, c);
    bool dy = (b.y > a.y && b.y < c.y);

    return !(dx && dy);
}

bool solve() {
    if (n <= 2)
        return true;

    for (int i = 0; i < n-2; i++) {
        for (int j = i+1; j < n-1; j++) {
            for (int k = j+1; k < n; k++) {
                /* printf("(%d,%d) (%d,%d), (%d,%d)\n", */
                /*     a[i].x, a[i].y, a[j].x, a[j].y, a[k].x, a[k].y); */
                if (!validate(a[i], a[j], a[k]))
                    return false;
            }
        }
    }

    return true;
}

int main() {
    cin >> T;

    while (T--) {
        cin >> n;
        a = vector<intp>(n);
        for (int i = 0; i < n; i++)
            cin >> a[i].x >> a[i].y;
        sort(a.begin(), a.end());
        cout << (solve() ? "YES\n" : "NO\n");
    }

    return 0;
}