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.
import sys
s = input()
n = int(s)
c = "1"*len(s)
c = int(c)
if(n>=c):
	print(pow(2,len(s))-1)
	sys.exit()
f = 0
i = 0
t = 0
while(f == 0):
	s = "{0:b}".format(i)
	it = int(s)
	if(n>=it):
		t = it
	else:
		f = 1
	i+=1
print(int(str(t),2))