#include<iostream>
using namespace std;
int main()
{
	int x;
    
	cin>>x;

	while(x)
	{
		
                int n;
                cin>>n;
                int a[n],b[n];
                int z,y;
                if(n==2 || n==3)
                {
                    for(int i=1;i<=n;i++)
                    {
                        cin>>z>>y;
                    }
                    cout<<"YES"<<"\n";
                }
                else
                {

                    for(int i=1;i<=n;i++)
                    {
                        a[i]=0;
                        b[i]=0;
                    }

                    for(int i=1;i<=n;i++)
                    {
                        cin>>z;
                        cin>>y;
                        a[i]=z;
                        b[i]=y;
                    }

                        int flag=0;
                    for(int i=1;i<=n;i++)
                    {
                        for(int j=i+1;j<=n;j++)
                        {
                            if(a[i]!=a[j] || b[i]!=b[j] )
                            {
                                flag=1;
                            }


                        }

                    }
                    if(flag==0)
                    {
                        cout<<"YES"<<"\n";
                    }
                    else
                    cout<<"NO"<<"\n";

            }
        x--;
    }
	
}