#include <bits/stdc++.h>

using namespace std;

#define MAX 100005
int trie[MAX][10];
int sz = 0;
int end_here[MAX];

void add(string s)
{
    int v = 0;
    for(int i=0; i<s.length(); i++){
        int x = s[i] - '0';
        if(trie[v][x] == -1) trie[v][x] = ++sz;
        v = trie[v][x];
    }
    end_here[v]++;
}

bool search(string s)
{
    int v = 0;
    for(int i=0; i<s.length(); i++){
        int x = s[i] - '0';
        if(trie[v][x] == -1) return false;
        v = trie[v][x];
        if(end_here[v]) return true;
    }
    return true;
}

int main()
{
    //freopen("in.txt", "r", stdin);
    //freopen("out.txt", "w", stdout);
    int cases;
    scanf("%d", &cases);
    int caseno = 0;
    while(cases--){
        memset(trie, -1, sizeof trie);
        memset(end_here, 0, sizeof end_here);
        sz = 0;
        int n;
        scanf("%d", &n);
        bool flag = true;
        for(int i=0; i<n; i++){
            string str;
            cin >> str;
            if(search(str)){
                flag = false;
            }
            add(str);
        }
        if(flag) printf("Case %d: YES\n", ++caseno);
        else printf("Case %d: NO\n", ++caseno);
    }
}