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 main() {
  string s;
  cin >> s;
  int n = s.length(), i, j;
  long long int a = 0;
  for (i = 0; i < n; i++) {
    if (s[i] - '0' > 1) {
      for (j = i; j < n; j++) {
        s[j] = '1';
      }
      break;
    }
  }
  for (i = n - 1; i >= 0; i--) {
    if (s[i] == '1') {
      a = a + pow(2, n - 1 - i);
    }
  }
  cout << a;
}
