def find_letter(n):
    # Calculate the repetition number and the count of letters printed up to that point
    repetition_num = (n - 1) // 26
    letter_count = (1 + 26) * 26 // 2 * repetition_num
    
    # Calculate the index of the letter within its repetition
    index_within_repetition = n - letter_count - 1
    
    # Calculate the letter based on its index within its repetition
    return chr(ord('A') + index_within_repetition)

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