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<vector<unsigned long long> > arr(10, vector<unsigned long long>());
  arr[0] = vector<unsigned long long>(1, 1);
  int count = 1;
  int i = 1;
  while (1) {
    unsigned long long x = 0;
    bool flag = false;
    for (vector<unsigned long long>::iterator it = arr[i - 1].begin();
         it != arr[i - 1].end(); ++it) {
      if (*it * 10 > N) {
        flag = true;
        break;
      }
      ++count;
      arr[i].push_back(*it * 10);
      if (*it * 10 + 1 > N) {
        flag = true;
        break;
      }
      ++count;
      arr[i].push_back(*it * 10 + 1);
    }
    ++i;
    if (flag) break;
  }
  cout << count;
  return 0;
}
