from math import sqrt, floor

T = int(input())
for case in range(1,T+1):
    N = int(input())-1

    # After i iterations, we have used
    # 26 + 26*2 + 26*3 + ... + 26*i = 26 * i * (i+1)/2 = 13*i*(i+1)
    # characters.
    # Hence, we can compute 13*i*(i+1) = N ==> 13i² + 13i - N = 0
    # ==> i = (-13 + sqrt(169 + 52N))/26

    i = floor((-13 + sqrt(169 + 52*N)) / 26)
    N -= 13*i*(i+1)
    N //= (i+1)
    ans = chr(ord("A") + N)

    print(f"Case #{case}: {ans}")