import sys

p = sys.stdin.readline().strip()

if p.startswith("0x"):
    p = p[2:]

result = 0

for i, y in enumerate(reversed(p)):
    if '0' <= y <= '9':
        num =ord(y) - ord('0')
    elif 'A' <= y <= 'F':
        num =10 + ord(y) - ord('A')
    else:
        continue

    result += num * (16 ** i)

print(result)

#startswith对照前面的值，reversed()反转，enumerate()为元素添加索引，ord()字符对于的码