#include <bits/stdc++.h>

using namespace std;

typedef long long int ll;

const int NMax = 2e5 + 5;
const int LIM = 1e9;

bool bad;

inline void check(int a, int b, int xm, int ym, int xM, int yM){

    bool fi, se;
    fi = se = false;
    if(a == xm){
        fi = true;
        if(b < ym || b > yM) bad = true;
    } else {
        if(a == xM){
            fi = true;
            if(b < ym || b > yM) bad = true;
        }
    }
    if(b == ym){
        se = true;
        if(a < xm || a > xM) bad = true;
    } else {
        if(b == yM){
            se = true;
            if(a < xm || a > xM) bad = true;
        }
    }

    if(fi == false && se == false) bad = true;

}

int main(){

    ios::sync_with_stdio(false);
    cin.tie(NULL);

    int t;
    cin >> t;

    while(t--){

        int n;
        cin >> n;

        pair < int, int > v[105];
        int xm, ym, xM, yM;
        xm = ym = INFINITY;
        xM = yM = -INFINITY;
        for(int i = 1; i <= n; i++){

            int a, b;
            cin >> a >> b;

            v[i] = {a, b};
            xm = min(a, xm);
            ym = min(b, ym);
            xM = max(a, xM);
            yM = max(b, yM);

        }

        bad = false;
        for(int i = 1; i <= n; i++){

            check(v[i].first, v[i].second, xm, ym, xM, yM);

        }

        if(bad == false){
            cout << "YES\n";
        } else {
            cout << "NO\n";
        }

    }
    return 0;

}