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;
vector<int> v;
void getans(string s, int left) {
  if (left == 0) {
    v.push_back(stoi(s));
  } else {
    getans(s + '0', left - 1);
    getans(s + '1', left - 1);
  }
}
int countdigit(int n) {
  int ans = 0;
  while (n > 0) {
    ans++;
    n = n / 10;
  }
  return ans;
}
int main() {
  int n;
  cin >> n;
  int p = countdigit(n);
  string s;
  getans(s, p);
  sort(v.begin(), v.end());
  int ans = 0;
  for (int i = 0; i < v.size(); i++) {
    if (v[i] <= n) {
      ans = i;
    } else {
      break;
    }
  }
  cout << ans;
}
