def convert_to_title(n):
    if not str(n).isdigit() or int(n) <= 0:
        print("Invalid input")
        return
    n = int(n)
    result = ""
    while n > 0:
        n -= 1
        remainder = n % 26
        result= chr(65 + remainder )+result
        n = n // 26
    print(result)
n = input()
number_to_title(n)