#include <cmath>
#include <cstdlib>
#include <cstdio>
#include <climits>
#include <functional>
#include <bitset>
#include <cstring>
#include <iostream>
#include <algorithm>
#include <sstream>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <set>
#include <map>
using namespace std;

int main() {
    int q;
    cin>>q;
    for (int i=0; i<q; ++i) {
        int n;
        cin>>n;
        vector<int> vx(n), vy(n);
        for (int i=0; i<n; ++i)
            cin>>vx[i]>>vy[i];
        vector<int> tx(vx), ty(vy);
        sort(tx.begin(), tx.end());
        sort(ty.begin(), ty.end());
        int lbx=tx[0], ubx=tx.back(), lby=ty[0], uby=ty.back();
        bool ok=1;
        for (int i=0; i<n; ++i) {
            if (vx[i]!=lbx && vx[i]!=ubx && vy[i]!=lby && vy[i]!=uby) {
                ok=0;
                break;
            }
        }
        if (ok) cout<<"YES\n";
        else cout<<"NO\n";
    }
    return 0;
}