// *** Copyright@RjStyles *** //

#include <map>
#include <set>
#include <cmath>
#include <queue>
#include <stack>
#include <cstdio>
#include <vector>
#include <ctype.h>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <algorithm>
using namespace std;

#define pb(val) push_back(val)
#define ull unsigned long long
#define ll long long
#define rep(i, s, e) for(int i=s; i<e; i++)
#define repr(i, s, e) for(int i=s; i<e; i--)
#define endl '\n'
#define vi vector<int>
#define	all(a) a.begin(), a.end()

template<typename T>void read(T &x) {
    register T c = getchar_unlocked(); x = 0; int t = 0;
    if (c == '-') t = 1, c = getchar_unlocked();
    for (; (c < 48 || c>57); c = getchar_unlocked());
    for (; c > 47 && c < 58; c = getchar_unlocked()) {
        x = (x << 1) + (x << 3) + c - 48;
    }
    if (t) x = -x;
}

int main() {
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    int q; cin>>q;
    while(q--) {
        int n; cin>>n;
        set<pair<int, int> > s;
        int x1 = 100000, y1 = 100000, x2 = -1000000, y2 = -1000000;
        while(n--) {
            int x, y; cin>>x>>y;
            if(x < x1) x1 = x;
            if(y < y1) y1 = y;
            if(x > x2) x2 = x;
            if(y > y2) y2 = y;
            s.insert(pair<int, int>(x, y));
        }
        set<pair<int, int> >::iterator it;
        bool f = true;
        for(it = s.begin(); it != s.end(); it++) {
            if(!(((it->first >= x1 && it->first <= x2) && (it->second == y1 || it->second == y2)) || ((it->first == x1 || it->first == x2) && (it->second >= y1 && it->second <= y2)))) {
                f = false;
                break;
            }
        }
        if(f) cout<<"YES"<<endl;
        else cout<<"NO"<<endl;
    }
    return 0;
}