#include <bits/stdc++.h>
#include <algorithm>

#define pb push_back
#define mp make_pair
#define mt make_tuple
#define ll long long unsigned
#define pii pair<int,int>
#define tii tuple <int,int,int>
#define N 1000005
#define mod 2000003
#define X first
#define Y second
#define eps 0.0000000001
#define all(x) x.begin(),x.end()
#define tot(x) x+1,x+n+1
using namespace std;
int q,n,m,i,j,k,l,ok,OK,x1,x2,y3,y2,x[15],y[15];
int main()
{
    cin.sync_with_stdio(0);
    cout.sync_with_stdio(0);
    cin>>q;
    for(; q; q--)
    {
        cin>>n;
        for(i=1; i<=n; i++)

            cin>>x[i]>>y[i];

        OK=0;

        for(i=1; i<=n&&!OK; i++)
            for(j=1; j<=n&&!OK; j++)
                for(k=1; k<=n&&!OK; k++)
                    for(l=1; l<=n&&!OK; l++)
                    {
                        x1=x[i];
                        x2=x[j];
                        y3=y[k];
                        y2=y[l];
                        ok=1;
                        for(m=1; m<=n; m++)
                        {
                            if(((x[m]==x1||x[m]==x2)&&y[m]>=min(y2,y3)&&y[m]<=(max(y3,y2)))||((y[m]==y3||y[m]==y2))&&x[m]<=max(x2,x1)&&x[m]>=min(x2,x1))
                                ;
                            else
                                ok=0;
                        }
                        if(ok)
                        {
                            cout<<"YES\n";
                            OK=1;
                            break;
                        }
                    }
        if(!OK)
            cout<<"NO\n";
    }
    return 0;
}