# Arup Guha
# 2/1/2025
# Odd Man Out
# https://open.kattis.com/problems/oddmanout

nC = int(input())

# Process cases.
for loop in range(1, nC+1):

    # Reading in all of the input.
    nGuests = int(input())
    nums = [int(x) for x in input().split()]

    guests = set()

    # For each number add it, if it's not in, remove if it's it.
    for x in nums:

        if not (x in guests):
            guests.add(x)
        else:
            guests.remove(x)

    print("Case #", loop, ": ", sep="", end="")
    for x in guests:
        print(x)