import fileinput
import sys

sys.setrecursionlimit(10**6)

lines = fileinput.input()

def read(conv=str, sep=None):
    global lines
    line = lines.readline().strip()
    if sep is None:
        return conv(line)
    else:
        return [conv(token) for token in line.split(sep)]

def eprint(*args, **kwargs):
    print(*args, file=sys.stderr, **kwargs)

def solve(N):
    i = 1
    while N >= 26*i:
        N -= 26*i
        i += 1
    k = N // i
    return chr(ord('A') + k)

T = read(int)
for t in range(T):
    N = read(int)
    sol = solve(N - 1)
    print("Case #{0}:".format(t + 1), sol)