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;
const long long MOD = 1000 * 1000 * 1000 + 7;
const double PI = 3.14159265;
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int n;
  cin >> n;
  std::vector<int> v;
  for (int i = 1; i < 513; ++i) {
    string s;
    int dum = i;
    while (dum > 0) {
      int x = dum % 2;
      dum /= 2;
      if (x)
        s += "1";
      else
        s += "0";
    }
    reverse(s.begin(), s.end());
    stringstream geek(s);
    int y = 0;
    geek >> y;
    v.push_back(y);
  }
  vector<int>::iterator lower;
  lower = upper_bound(v.begin(), v.end(), n);
  cout << lower - v.begin() << endl;
  return 0;
}
