#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
using namespace std;


int main() {
    int T;
    cin>>T;
    for (auto t = 0; t<T; t++) {
        int n;
        cin>>n;
        vector<int> xcords(n), ycords(n);
        vector<pair<int,int> > pairs(n);
        for (auto i = 0; i<n; i++) {
            int x, y; cin>>x>>y;
            pairs[i] = pair<int, int>(x,y);
            xcords[i] = x; ycords[i] = y;
        }
        int x1 = *min_element(xcords.begin(), xcords.end());
        int x2 = *max_element(xcords.begin(), xcords.end());
        int y1 = *min_element(ycords.begin(), ycords.end());
        int y2 = *max_element(ycords.begin(), ycords.end());
        bool flag = true;
        for (auto ii: pairs) {
            auto v1 = ii.first;
            auto v2 = ii.second;
            if (!(((v1==x1 || v1==x2) /*&& (v2>=y1 && v2<=y2)*/) ||
                ((v2==y1 || v2==y2) /*&& (v1>=x1 && v1<=x1)*/))) {
                cout<<"NO"<<endl;
                flag = false;
                break;
            }
        }
        if (flag) cout<<"YES"<<endl;
    } 
    return 0;
}