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>
using namespace std;
int main() {
  int n;
  scanf("%d", &n);
  int i, j, k, l;
  int ans = 0;
  for (i = 0; i < 10; i++) {
    int x = 1 * pow(10, i);
    if (x > n) break;
    for (j = x; j < (2 * x) && j <= n; j++) {
      ans++;
      int m = j;
      while (m > 0) {
        int t = m % 10;
        m = m / 10;
        if (t == 0 || t == 1)
          continue;
        else {
          ans--;
          break;
        }
      }
    }
  }
  cout << ans << endl;
  return 0;
}
