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() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long n;
  cin >> n;
  long long d = (long long)(log10(n));
  d++;
  long long ans = 0;
  vector<int> dig;
  while (n != 0) {
    dig.push_back(n % 10);
    n = n / 10;
  }
  reverse(dig.begin(), dig.end());
  for (int i = 0; i < dig.size(); i++) {
    if (dig[i] > 1) {
      ans += 1 << (d - i);
      break;
    } else if (dig[i] > 0) {
      ans += 1 << (d - 1 - i);
    }
  }
  bool flag = true;
  for (int i = 0; i < dig.size(); i++) {
    if (dig[i] != 0 && dig[i] != 1) {
      flag = false;
      break;
    }
  }
  if (!flag) {
    ans--;
  }
  cout << ans << '\n';
}
