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() {
  vector<int> dig(10, 1);
  int i;
  for (i = 1; i < 10; i++) {
    dig[i] = pow(2, i - 1) + dig[i - 1];
  }
  int n;
  cin >> n;
  string s = to_string(n);
  n = s.length();
  bool flag = false;
  int sum = 0;
  for (i = 0; i < n; i++) {
    if (s[i] == '1') {
      sum += dig[n - 1 - i];
    } else if (s[i] == '0') {
      sum += 0;
    } else {
      sum += dig[n - i];
      flag = true;
      break;
    }
  }
  if (flag) {
    cout << sum - 1;
  } else {
    cout << sum;
  }
}
