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.
#include <bits/stdc++.h>
int f(int x) {
  int i, j, res = 0;
  for (i = j = 1; i <= x; i *= 2, j *= 10)
    ;
  for (i /= 2, j /= 10; i; i /= 2, j /= 10) res += x / i % 2 * j;
  return res;
}
int main() {
  int i, n;
  scanf("%d", &n);
  for (i = 1; f(i) <= n; i++)
    ;
  printf("%d", i - 1);
}
