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 cn = 0;
string s, t;
void dfs(string a) {
  if (a.size() == s.size()) {
    if (a <= s && a > t) {
      cn++;
    }
    return;
  }
  dfs(a + '1'), dfs(a + '0');
  return;
}
int main() {
  cin >> s;
  for (int i = 0; i < s.size(); ++i) {
    t += '0';
    if (s[i] > '1')
      for (int j = i; j < s.size(); ++j) s[j] = '1';
  }
  dfs("");
  cout << cn;
}
