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() {
  string str[1025];
  for (int i = 1; i <= 1024; i++) {
    string temp = "";
    int fuck = i;
    while (fuck > 0) {
      temp += fuck % 2 + '0';
      fuck /= 2;
    }
    reverse(temp.begin(), temp.end());
    str[i] = temp;
  }
  sort(str, str + 1025);
  long long int a[1025];
  for (int i = 1; i <= 1024; i++) {
    a[i] = stoll(str[i]);
  }
  int n;
  cin >> n;
  int count = 0;
  for (int i = 1; i <= 1024; i++) {
    if (n >= a[i]) {
      ++count;
    }
  }
  cout << count;
}
