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.
# 9.C
import sys

def generate():
	a = ['1']
	for l in xrange (2, 10):
		last = len (a)
		a.append ('1' + '0'* (l-1))
		for i in xrange (last):	
			lenn = len (a[i])
			a.append ('1' + '0'* (l-1-lenn) + a[i])
	a.append ('1' + '0'*9)
	return a

n = int (raw_input())
a = generate()
x = [int (it) for it in a]
x.append (1900000000) # sentinel
#for i in xrange (len(x)):
#	print '%3d) %10d' % (i+1, x[i])
i = 0
while n >= x[i]:
	i += 1
print i	
	


