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, sum = 0;
  cin >> n;
  if (n < 10 && n >= 1) {
    cout << 1;
    return 0;
  }
  string s = to_string(n);
  for (int i = 0; i < s.size() - 1; i++) {
    sum = sum + pow(2, i);
  }
  if (s[0] > 49) {
    sum = sum + pow(2, s.size() - 1);
    cout << sum;
    return 0;
  }
  for (int i = 1; i < s.size() - 1; i++) {
    if (s[i] == 49) {
      sum = sum + pow(2, s.size() - i - 1);
    }
    if (s[i] > 49) {
      sum = sum + pow(2, s.size() - i);
      cout << sum;
      return 0;
    }
  }
  if (s[s.size() - 1] > 48) {
    sum = sum + 2;
  } else {
    sum = sum + 1;
  }
  cout << sum;
}
