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 num(int n) {
  int k = 0, m = 4, p = 1, t = n;
  if (!n)
    return 0;
  else if (n < 10)
    return 1;
  else if (n == 10)
    return 2;
  else if (n < 100)
    return 3;
  else if (n == 100)
    return 4;
  else {
    while (n > 9) {
      n /= 10;
      k++;
      p *= 10;
    }
    k--;
    while (k--) m *= 2;
    if (n > 1)
      return m - 1;
    else if (!n)
      return 0;
    else {
      t %= p;
      return m / 2 + num(t);
    }
  }
}
int main() {
  int n;
  cin >> n;
  cout << num(n) << endl;
  return 0;
}
