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 n, k, sum, j, i, v;
string s;
int main() {
  cin >> s;
  n = 1;
  k = s.size();
  for (j = 0; j < s.size(); j++) {
    k--;
    if (s[j] > '1') {
      for (v = 0; v < s.size(); v++) s[v] = '1';
    }
    if (s[j] > '0') {
      for (i = k; i > 0; i--) n *= 2;
      sum += n;
      n = 1;
    }
  }
  cout << sum;
}
