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() {
  string second;
  cin >> second;
  int ans = 0;
  bool ok = false;
  for (int i = 0; i < second.length(); i++) {
    int d = second[i] - 48;
    if (d > 1) {
      ok = true;
    }
    if (ok) d = 1;
    ans = ans + d * (pow(2, second.length() - i - 1));
  }
  cout << ans;
  return 0;
}
