One beautiful July morning a terrible thing happened in Mainframe: a mean virus Megabyte somehow got access to the memory of his not less mean sister Hexadecimal. He loaded there a huge amount of n different natural numbers from 1 to n to obtain total control over her energy.

But his plan failed. The reason for this was very simple: Hexadecimal didn't perceive any information, apart from numbers written in binary format. This means that if a number in a decimal representation contained characters apart from 0 and 1, it was not stored in the memory. Now Megabyte wants to know, how many numbers were loaded successfully.

Input

Input data contains the only number n (1 ≤ n ≤ 109).

Output

Output the only number — answer to the problem.

Examples

Input

10


Output

2

Note

For n = 10 the answer includes numbers 1 and 10.
def main():
	n = list(raw_input())
	x = list()
	#print n
	i=0

	while i<len(n):
		if n[i]=='0' or n[i]=='1':
			x.append(n[i])
			i = i +1
		else:
			break
		

	#print len(n)
	#print i
	b= str(''.join(x)+'1'*(len(n)-i))
	print int(b,2)


main()