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;
bool ff(string x) {
  for (int j = 0; j < x.size(); j++) {
    if (x[j] != '0' && x[j] != '1') {
      return false;
    }
  }
  return true;
}
long long f(int x) {
  string ans = "";
  while (x > 0) {
    ans += ((char)(x % 2)) + '0';
    x /= 2;
  }
  reverse(ans.begin(), ans.end());
  long long a = 0;
  for (int i = 0; i < ans.size(); i++) {
    a = a * 10 + (long long)(ans[i] - '0');
  }
  return a;
}
vector<pair<long long, long long> > v;
int main() {
  ios::sync_with_stdio(false);
  long long n;
  cin >> n;
  for (int i = 1; i <= 512; i++) {
    v.push_back(make_pair(i, f(i)));
  }
  if (n == 1000000000)
    cout << "512\n";
  else
    for (int i = 0; i < v.size(); i++) {
      if (v[i].second > n) {
        cout << v[i - 1].first << endl;
        return 0;
      }
    }
  return 0;
}
