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.
'''                      
   	
   			 ||Sri:||                 

                      __|
 ______________|_________________________
      |    |   ___|    |    |    ___|      |      |    |___
 /\  /\    |   |___    |    |   |___|      |      |    |___|
/  \/  \   |   ___|    |    |         |_/    |___|    |___

I am a beginner. Feel free to send tutorials/help to srinivasan1995@gmail.com.

Codeforces, SPOJ handle: desikachariar.
Hackerrank, Codechef handle: Prof_Calculus.

Advices/Help are welcome. You will definitely get a thanks in return. Comments to be avoided.

College: International Institute of Information Technology, Bangalore.

'''

import math

def fn():
	return

if __name__ == '__main__':
	x = [int(p) for p in raw_input()]
	for i in range(len(x)):
		if x[i] > 1:
			x[i] = 1
			for j in range(i, len(x)):
				x[j] = 1
			break
	x = "".join(str(p) for p in x)
	print int(x, 2)
	
