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;
long long int dec(long long int i) {
  vector<int> v;
  while (i) {
    if (i & 1)
      v.push_back(1);
    else
      v.push_back(0);
    i = i >> 1;
  }
  long long int ans = 0, pro = 1;
  for (int j = 0; j < v.size(); j++) {
    if (v[j]) ans += pro;
    pro = pro * 10;
  }
  return ans;
}
int main() {
  long long int n;
  cin >> n;
  int ans = 0;
  for (long long int i = 1;; i++) {
    if (dec(i) > n)
      break;
    else
      ans++;
  }
  cout << ans << endl;
}
