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 inf = 1e9;
int main() {
  ios::sync_with_stdio(0);
  cin.tie(0), cout.tie(0);
  string n;
  cin >> n;
  int id = inf;
  for (int i = 0; i < n.size(); i++) {
    if (n[i] > '1') {
      id = i;
      break;
    }
  }
  if (id < 20)
    for (int i = id; i < n.size(); i++) n[i] = '1';
  int ans = 0;
  for (int i = 0; i < n.size(); i++) {
    ans += (n[i] - '0') * (1ll << (n.size() - i - 1));
  }
  cout << ans << endl;
  return 0;
}
