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[35000];
int al;
int flag[15];
void dfs(int nn) {
  if (nn >= 10) {
    int num = 0;
    for (int i = 0; i < nn; i++) {
      num *= 10;
      num += flag[i];
    }
    a[al++] = num;
    return;
  }
  flag[nn] = 1;
  dfs(nn + 1);
  flag[nn] = 0;
  dfs(nn + 1);
}
int main() {
  al = 0;
  dfs(0);
  sort(a, a + al);
  int n;
  while (scanf("%d", &n) != EOF) {
    int ans = upper_bound(a, a + al, n) - a - 1;
    printf("%d\n", ans);
  }
  return 0;
}
