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;
void solve(int &res, string &s, int l) {
  if (l == 0) {
    res += (stoi(s) <= n);
    return;
  }
  s.push_back('0');
  solve(res, s, l - 1);
  s.pop_back();
  s.push_back('1');
  solve(res, s, l - 1);
  s.pop_back();
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cin >> n;
  int res = -1;
  string s;
  solve(res, s, 10);
  cout << res;
  return 0;
}
