def find_letter(n):
lo, hi = 1, 60
while lo < hi:
mid = (lo + hi) // 2
length = 26 * (2mid - 1)
if n > length:
lo = mid + 1
else:
hi = mid
k = lo
offset = n - 1 - 26 * (2(k-1) - 1)
return chr(ord('A') + offset % 26)


t = int(input())
for i in range(t):
n = int(input())
letter = find_letter(n)
print("Case #{}: {}".format(i+1, letter))