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.
from itertools import combinations

n = int(input())
a = '1010101010101010101010'
b = []

for i in range(1,11):
	s = list(set(combinations(a,i)))
	for j in range(len(s)):
		s[j] = int(''.join(s[j]))
	b.extend(s)
	
b = sorted(set(b))
m = len(b)

#print(b)

#print(m)

for i in range(m):
	if(b[i] > n):
		print(i-1)
		exit()

print(n)	