alphabet = 'ABCDEFGHIJKLMNOPQRSTUVWXYZ'

def f(x):
    return 13*x*(x+1)

# mth iteration has 13n(n+1) letters
def bsearch(n):
    m = 0
    M = n
    while M - m > 1:
        mid = (m+M)//2
        if f(mid) <= n:
            m = mid
        else:
            M = mid
    return m

t = int(input())
for u in range(t):
    n = int(input())
    m = bsearch(n)
    extra = n - f(m)
    idx = (extra-1)//(m+1)
    ans = alphabet[idx]
    
    print('Case #' + str(u+1) + ':', ans)