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;
  cin >> n;
  string s = "";
  while (n != 0) {
    int x = n % 10;
    s += char(x + '0');
    n /= 10;
  }
  if (s[s.length() - 1] != '1') {
    cout << pow(2, s.length()) - 1;
  } else {
    int res = 0;
    for (int i = 0; i < s.length(); i++) {
      if (s[i] != '0') {
        res += pow(2, i);
      } else {
        for (int j = i; j < s.length(); j++) {
          if (s[j] - '0' > 1) {
            res += pow(2, i);
            break;
          }
        }
      }
    }
    cout << res;
  }
  return 0;
}
