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() {
  int n;
  cin >> n;
  int res = 0;
  long long int x = 1;
  int a = 1;
  while (n >= x) {
    x = 0;
    long long int ten = 1;
    for (int i = 0; i < 11; i++) {
      if ((1 << i) & a) {
        x += ten;
      }
      ten *= 10;
    }
    if (x <= n) res++;
    a++;
  }
  cout << res << endl;
}
