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 n, sch, k, j;
string s;
string convertInt(int number) {
  stringstream ss;
  ss << number;
  return ss.str();
}
string Prover(int n) {
  int k;
  string s;
  s = convertInt(n);
  k = s.length();
  for (int i = 0; i < k; i++)
    if (s[i] != '0' && s[i] != '1') return '#' + s;
  return s;
}
int main() {
  sch = 0;
  cin >> n;
  s = Prover(n);
  if (s[0] == '#') {
    int p;
    s.erase(0, 1);
    for (int i = 0; i < (int)s.length(); i++)
      if (s[i] > '1') {
        p = i;
        break;
      }
    for (int i = p; i < (int)s.length(); i++) s[i] = '1';
  }
  j = 1;
  for (int i = (int)s.length() - 1; i >= 0; i--) {
    if (s[i] == '1') sch += j;
    j *= 2;
  }
  cout << sch;
  return 0;
}
