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

typedef pair <int, int> pii;
const int MAX = 20;
const int oo = 1e5;
int q, n;
pii cor[MAX];
pii bot_lef, top_rig;

bool inRec(const pii& cor){
    bool check = false;
    if (cor.first == bot_lef.first || cor.first == top_rig.first)
        check = check || (cor.second >= bot_lef.second && cor.second <= top_rig.second);
    if (cor.second == bot_lef.second || cor.second == top_rig.second)
        check = check || (cor.first >= bot_lef.first && cor.first <= top_rig.first);
    return check;
}

int main(){
    //freopen("in.txt", "r", stdin);
    ios_base::sync_with_stdio(0);
    cin >> q;
    while (q--){
        cin >> n;
        bot_lef = pii(oo, oo);
        top_rig = pii(-oo, -oo);
        for (int i = 0; i < n; ++i){
            cin >> cor[i].first >> cor[i].second;
            bot_lef.first = min(bot_lef.first, cor[i].first);
            bot_lef.second = min(bot_lef.second, cor[i].second);

            top_rig.first = max(top_rig.first, cor[i].first);
            top_rig.second = max(top_rig.second, cor[i].second);
        }

        bool check = true;
        for (int i = 0; i < n; ++i)
        if (!inRec(cor[i])){
            check = false;
            break;
        }

        cout << (check ? "YES\n" : "NO\n");
    }
    return 0;
}