binary_str = input().strip()
if not all(ch in '01' for ch in binary_str) or len(binary_str) == 0 or len(binary_str) > 32:
print("Invalid Input")
else:
n = len(binary_str)
if binary_str[0] == '0':
print(int(binary_str,2))
else:
value = int(binary_str, 2) - (1 <<n)
print(value)