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
input = sys.stdin.readline
I = lambda : list(map(int,input().split()))


# Hex nums
#flop [not conv to bin exact :))]
n,=I()
x=[]
for i in range(1,2**10+1):
	k=format(i,'b');p=0
	o=len(k)
	for j in range(o):
		if k[o-j-1]=='1':
			p+=10**(j)
	x.append(p)
an=0
for j in range(len(x)):
	if x[j]>n:
		an=j;break
print(an)