def get_char_nth(n):
    alpha = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'
    i = 1
    while n > i*26:
        n -= i*26
        i += 1
    indx = (n-1) // i
    return alpha[indx]

# main function to read input and print output
def main():
    test_case = int(input())
    for i in range(1, test_case+1):
        n = int(input())
        ans = get_char_nth(n)
        print("Case #{}: {}".format(i, ans))

if _name_ == '_main_':
    main()