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 ans = 1;
  for (int i = 1; i < 10; i++) {
    int tmp;
    for (int j = 0; j < (1 << i); j++) {
      tmp = 1;
      for (int k = 0; k < i; k++) tmp = tmp * 10 + ((j & (1 << k)) ? 1 : 0);
      if (tmp <= n) ans++;
    }
  }
  printf("%d\n", ans);
  return 0;
}
