import static java.util.Arrays.deepToString;

import java.io.BufferedReader;

import java.io.FileReader;

import java.io.IOException;

import java.io.PrintWriter;

import java.util.ArrayList;

import java.util.Comparator;

import java.util.List;

import java.util.Set;

import java.util.StringTokenizer;

import java.util.TreeSet;

public class Solution {

private static void debug(final Object...objs) {

System.out.println(deepToString(objs));

}

public class Order implements Comparator<String> {

@Override

public int compare(final String s1, final String s2) {

final int len1 = s1.length();

final int len2 = s2.length();

if(len1 != len2) return len1 - len2;

return s1.compareTo(s2);

}

}

List<String> c = null;

private boolean contains(final String t, final int index) {

for (int i = 0; i < c.size(); i++) {

if (i != index)

if (c.get(i).contains(t)) return true;

}

return false;

}

private String solveCase() throws IOException {

final int N = nextInt();

c = new ArrayList<String>();

final List<Set<String>> ls = new ArrayList<Set<String>>();

for (int i = 0; i < N; i++) {

final String name = nextLine().toUpperCase();

c.add(name);

final Set<String> s = new TreeSet<String>(new Order());

for (int m = 0; m < name.length(); m++) {

for (int n = m + 1; n < name.length() + 1; n++) {

s.add(name.substring(m, n));

}

}

ls.add(s);

}

if (N == 1) return "\"\"";

// debug(c);

// debug(ls);

final StringBuilder res = new StringBuilder();

for (int i = 0; i < N; i++) {

String r = null;

final Set<String> s = ls.get(i);

for (final String t : s) {

if (!contains(t, i)) {

r = t;

break;

}

}

if (r == null) res.append(":(\n");

else res.append("\"" + r + "\"\n");

}

return res.toString();

}

private void solve() throws IOException {

final int testNumber = nextInt();

for (int test = 0; test < testNumber; test++) {

final String result = "Case #" + (test + 1) + ":\n" + solveCase();

pw.print(result);

System.out.print(result);

}

}

private BufferedReader br;

private PrintWriter pw;

private StringTokenizer st;

int nextInt() throws IOException {

return Integer.parseInt(next());

}

String nextLine() throws IOException {

return br.readLine();

}

String next() throws IOException {

while (st == null || !st.hasMoreTokens()) {

st = new StringTokenizer(br.readLine());

}

return st.nextToken();

}

public static void main(final String[] args) throws IOException {

new Solution().run();

}

private void run() throws IOException {

br = new BufferedReader(new FileReader("input.txt"));

pw = new PrintWriter("output.txt");

solve();

br.close();

pw.flush();

pw.close();

}

}