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() {
  int n;
  cin >> n;
  vector<int> arr;
  arr.push_back(1);
  int tmp = 1;
  for (int j = 1; j <= 10; j++) {
    tmp *= 10;
    arr.push_back(tmp);
    for (int i = 0; i < arr.size(); i++) {
      if (arr[i] == tmp) break;
      arr.push_back(tmp + arr[i]);
    }
  }
  int cnt = 0;
  for (int i = 0; i < arr.size(); i++)
    if (arr[i] > n)
      break;
    else
      cnt++;
  cout << cnt << endl;
  return 0;
}
