import sys
input = sys.stdin.readline

T=int(input())
for tests in range(T):
    N=int(input())

    OK=0
    NG=10**12

    while NG>OK+1:
        mid=(OK+NG)//2

        if mid*(mid+1)//2*26<=N:
            OK=mid
        else:
            NG=mid

    N-=OK*(OK+1)//2*26

    if N==0:
        ANS="Z"
    else:
        for i in range(26):
            if i*(OK+1)<N<=(i+1)*(OK+1):
                ANS=chr(i+65)

    print("Case #"+str(tests+1)+": "+str(ANS))