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() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n;
  cin >> n;
  int dig = 0, rev = 0;
  int copy = n;
  while (copy > 0) {
    dig++;
    rev = rev * 10 + (copy % 10);
    copy /= 10;
  }
  int num = 0;
  while (dig--) {
    if (rev % 10 > 1) {
      num += (1 << (dig + 1)) - 1;
      break;
    } else {
      num += (rev % 10) << dig;
      rev /= 10;
    }
  }
  cout << num;
  return 0;
}
