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 n;
void doit() {
  scanf("%d", &n);
  int ans = 1, k = 0;
  while (n > 0) {
    int p = n % 10;
    n /= 10;
    if (p == 1)
      ans += 1 << k;
    else if (p >= 2)
      ans = 1 << (k + 1);
    k++;
  }
  printf("%d\n", ans - 1);
}
int main() {
  doit();
  return 0;
}
