import math
import sys

CASE = "Case #"


def solve(n):
    if n <= 26:
        return chr(n + 64)
    n = n - 1
    delta = (1 / 4) + 2 * (n // 26)
    k = int((-1 / 2) + math.sqrt(delta))
    q = 26 * k * (k + 1) // 2
    m = (n % q) // (k + 1)
    return chr(m + 65)


def main():
    with sys.stdin as the_input:
        nb_cases = int(the_input.readline())
        for case in range(1, nb_cases + 1):
            n = int(the_input.readline())
            c = solve(n)
            print("Case #{}: {}".format(case, c))


if __name__ == "__main__":
    main()