#include <bits/stdc++.h>
using namespace std;
long long q,n;
struct cap
{
    int x,y;
} a[100];
int main()
{
    cin>>q;
    for (int i=1; i<=q; i++)
    {
        cin>>n;
        for (int j=1; j<=n; j++)
        {
            cin>>a[j].x >> a[j].y;
        }
        if (n==1)
        {
            cout<<"YES" <<endl;
            continue;
        }
        if (n==2)
        {
            if (a[1].x !=a[2].x && a[1].y !=a[2].y)
            {
                cout<< "NO" <<endl;
                continue;
            }
            else
            {
                cout<<"NO" <<endl;
                continue;
            }
        }
        if (n==3)
        {
            if (a[1].x ==a[2].x && a[1].y == a[3].y)
            {
                cout<<"YES"<<endl ;
                continue;
            }
            if (a[1].x ==a[3].x && a[1].y == a[2].y)
            {
                cout<<"YES" <<endl;
                continue;
            }
            if (a[1].x ==a[2].x && a[2].y == a[3].y)
            {
                cout<<"YES" <<endl;
                continue;
            }
            if (a[3].x ==a[2].x && a[2].y == a[1].y)
            {
                cout<<"YES" <<endl;
                continue;
            }
            if (a[3].x ==a[2].x && a[1].y == a[3].y)
            {
                cout<<"YES" <<endl;
                continue;
            }
            if (a[1].x ==a[3].x && a[2].y == a[3].y)
            {
                cout<<"YES" <<endl;
                continue;
            }
            cout<<"NO"<<endl;

        }
    }
    if (n>=4)
    {
        for (int b=1; b<=n; b++)
        {
            for (int c=1; c<=n; c++)
            {
                if ((a[b].x== a[c].x && a[b].y !=a[c].y) || (a[b].y ==a[c].y && a[b].x !=a[c].x) )
                {
                    for (int d=1; d<=n; d++)
                    {
                        if ((((a[d].x == a[b].x) && (a[d].x != a[c].x)) ||((a[d].x == a[c].x) && (a[d].x != a[b].x)) || ((a[d].y == a[b].y) && (a[d].y != a[c].y)) ||((a[d].y == a[c].y) && (a[d].y != a[b].y))) && (a[d].x !=a[b].x && a[d].y != a[b].y) && (a[d].x != a[c].x && a[d].y != a[c].y))
                        {
                            for (int e=1; e<=n; e++)
                            {
                                if (( (a[e].x == a[b].x && ( a[e].y == a[c].y || a[e].y ==a[d].y)) || ( a[e].y == a[b].y && ( a[e].x == a[c].x || a[e].x ==a[d].x)) || ( a[e].x == a[c].x && ( a[e].y == a[b].y || a[e].y ==a[d].y))|| ( a[e].y == a[c].y && ( a[e].x == a[b].x || a[e].x ==a[d].x)) || ( a[e].x == a[d].x && ( a[e].y == a[b].y || a[e].y ==a[c].y)) || ( a[e].y == a[c].y && ( a[e].x == a[b].x || a[e].x ==a[d].x))) && (a[e].x !=a[b].x && a[e].y !=a[b].y) && (a[e].x !=a[c].x && a[e].y !=a[c].y) && (a[e].x !=a[d].x && a[e].y !=a[d].y))
                                {
                                    cout <<"YES" <<endl;
                                    continue;
                                }
                            }
                        }
                    }
                }
            }
        }
        cout<<"NO" <<endl ;
    }
}