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 sys import stdin,stdout,setrecursionlimit,maxint,exit
setrecursionlimit(2*10**4)
def listInput():
 return map(long,stdin.readline().split())
def printBS(li):
 for i in xrange(len(li)-1):
  stdout.write("%d "%li[i])
 stdout.write("%d\n"%li[-1])
from math import ceil
def sin():
 return stdin.readline().rstrip()
def ways(i,n):
 d=0
 if i*10<=n:
  d+=1+ways(i*10,n)
 if i*10+1<=n:
  d+=1+ways(i*10+1,n)
 return d
n=input()
print ways(1,n)+1
 