def get_nth_char(n):
    alphabet = "ABCDEFGHIJKLMNOPQRSTUVWXYZ"
    i = 1
    while n > i * 26:
        n -= i * 26
        i += 1
    char_index = (n - 1) // i
    return alphabet[char_index]
t = int(input())
for case in range(1, t + 1):
    n = int(input())
    nth_char = get_nth_char(n)
    print(f"Case #{case}: {nth_char}")