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);
  int num;
  cin >> num;
  vector<int> answers;
  answers.emplace_back(1);
  for (int power = 1; power <= 9; power++) {
    int start = (int)(pow(10, power) + 1e-9);
    if (num < start) {
      cout << answers.size() << "\n";
      return 0;
    }
    answers.emplace_back(start);
    for (int i = 0; i < (int)(pow(2, power) - 1 + 1e-9); i++) {
      int next = start + answers[i];
      if (num < next) {
        cout << answers.size() << "\n";
        return 0;
      }
      answers.emplace_back(next);
    }
  }
}
