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;
void show(vector<int> a) {
  int i = 0;
  while (i < a.size()) {
    cout << a[i] << " ";
    i++;
  }
  cout << endl;
}
void show(map<int, int> a) {
  for (auto i = a.begin(); i != a.end(); i++) {
    cout << i->first << " " << i->second << endl;
  }
}
string numToBin(int a) {
  string s = "";
  while (a > 0) {
    s += to_string(a % 2);
    a /= 2;
  }
  reverse(s.begin(), s.end());
  return s;
}
int answer(int a) {
  int ans = 0;
  for (int i = 1; i < 513; i++) {
    if (stoi(numToBin(i)) > a)
      break;
    else
      ans++;
  }
  return ans;
}
int main() {
  int t;
  cin >> t;
  cout << answer(t) << endl;
}
