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;
const int N = (1 << 14) - 1;
int main() {
  long long int n;
  int ans = 0;
  cin >> n;
  for (int i = 1; i <= N; i++) {
    bitset<14> num(i);
    long long int pot = 1;
    long long int tmp = 0;
    for (int k = 0; k < num.size(); k++) {
      if (num[k]) {
        tmp += pot;
      }
      pot = pot * 10;
    }
    if (tmp > n) {
      ans = i - 1;
      break;
    }
  }
  cout << ans << '\n';
  return 0;
}
