import sys str = input() sum = 0 dic = {'A': 10, 'B': 11, 'C': 12, 'D': 13, 'E': 14, 'F': 15} for i in range(len(str) - 2): n = str[len(str) - 1 - i] if n in dic: sum += dic[n] * 16 ** i else: sum += (int(n) * 16 ** i) print(sum)