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 a[15];
int sum[15];
void init() {
  a[0] = sum[0] = 1;
  a[1] = 1;
  sum[1] = 1;
  for (int i = 2; i < 15; i++) {
    a[i] = a[i - 1] * 2;
    sum[i] = sum[i - 1] + a[i];
  }
}
int main() {
  char s[15];
  int ans;
  init();
  while (gets(s)) {
    ans = 0;
    int len = strlen(s);
    for (int i = 0; s[i]; i++) {
      if (s[i] > '1') {
        ans += sum[len - i];
        break;
      }
      if (s[i] == '1') {
        ans += a[len - i];
      }
    }
    printf("%d\n", ans);
  }
  return 0;
}
