#define filer() freopen("in.txt","r",stdin)
#define filew() freopen("out.txt","w",stdout)

#include<iostream>
#include<stdio.h>
#include<string.h>
#include<math.h>
#include<algorithm>
#include<queue>
#include<stack>
#include<vector>
#include <map>
#define INF 1<<29
#define SET(a, x) memset((a), (x), sizeof(a))
#define i64 long long
#define pb push_back
#define EPS 1e-9
using namespace std;

struct node
{
	bool endmark;
	node *next[10+1];
	node()
	{
		endmark=false;
		for(int i=0;i<10;i++) next[i]=NULL;
	}
}*root;

void insert(char *str,int len)
{
	node *curr=root;
	for(int i=0;i<len;i++)
	{
		int id=str[i]-'0';
		if(curr->next[id]==NULL)
			curr->next[id]=new node();
		curr=curr->next[id];
	}
	curr->endmark=1;

}
bool search(char *str,int len)
{
	node *curr=root;
	for(int i=0;i<len;i++)
	{
		int id=str[i]-'0';
		//if(curr->next[id]==NULL) return false;
		curr=curr->next[id];
	}
	for(int id=0;id<10;id++)
	{
	    if(curr->next[id]!=NULL)return false;
	}
	return true;
}



void del(node *cur)
{
      for(int i=0;i<10;i++)
             if(cur->next[i])
                  del(cur->next[i]) ;
          delete(cur) ;
}



char S[10009][12];

int main()
{
    //filer();
    int i,j,k ,T,cas=0;
    //scanf("%d%d",,&N,&T);
    scanf("%d",&T);
    int n;

    while(T--)
    {
        root=new node();
        scanf("%d",&n);
        for(i=0;i<n;i++)
        {
            scanf("%s",S[i]);
            insert(S[i],strlen(S[i]));
        }
        bool t=1;
        for(i=0;i<n;i++)
        {
            t=search(S[i],strlen(S[i]));
            if(!t)break;
        }
        if(!t)printf("Case %d: NO\n",++cas);
        else printf("Case %d: YES\n",++cas);
        del(root);
    }


    return 0;
}