#include <bits/stdc++.h>

using namespace std;

//#define FILE_IO

typedef pair<int, int> pii;

int N, ok, mxx, mxy, mnx, mny;
vector <pii> v;

int main()
{
    #ifdef FILE_IO
    freopen("1.in", "r", stdin);
    freopen("1.out", "w", stdout);
    #endif

    int T;
    scanf("%d", &T);
    while(T--)
    {
        scanf("%d", &N);
        mxx = mxy = -1000000;
        mnx = mny = 1000000;
        v.clear();
        for(int i = 1; i <= N; i++)
        {
            int x, y;
            scanf("%d%d", &x, &y);
            v.push_back({x, y});

            mxx = max(mxx, x);
            mnx = min(mnx, x);
            mxy = max(mxy, y);
            mny = min(mny, y);
        }

        int ok = 1;
        for(int i = 0; i < v.size(); i++)
            if(v[i].first != mnx && v[i].first != mxx && v[i].second != mny && v[i].second != mxy)
                ok = 0;

        if(ok)
            printf("YES\n");
        else
            printf("NO\n");

    }

    return 0;
}