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;
  int ans = 0;
  cin >> n;
  for (int i = 1; i <= (1 << 9); i++) {
    int k = 0;
    int pow = 1;
    for (int j = 0; j < 15; j++) {
      if ((i >> j) % 2) {
        k += pow;
      }
      pow *= 10;
    }
    if (n >= k) {
      ans++;
    }
  }
  cout << ans;
  return 0;
}
