from sys import stdin
input = stdin.readline
GI = lambda: int(input())
gi = lambda: list(map(int, input().split()))
T = GI()
def solve(id):
    N = GI() - 1
    # 26 * i
    left = 0
    right = 10**12
    while right - left > 1:
        mid = left + right >> 1
        if 26 * mid * (mid + 1) // 2 >= N:
            right = mid
        else:
            left = mid
    N -= 26 * left * (left + 1) // 2
    N //= left + 1
    return chr(65 + N % 26)

for i in range(1, T + 1):
    print("Case #%d: %s" % (i, solve(i)))