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 d[10] = {1, 2, 4, 8, 16, 32, 64, 128, 256, 512};
int main() {
  string s;
  cin >> s;
  int c = 0, n = s.size();
  for (int i = 0; i < int((s).size()); i++)
    if (s[i] != '0' && s[i] != '1') {
      for (int j = i; j < n; ++j) s[j] = '1';
      break;
    }
  for (int i = 0; i < int((s).size()); i++) c += d[n - i - 1] * (s[i] - '0');
  cout << c << endl;
  return 0;
}
