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;
long long f(long long n, long long x) {
  if (x >= n) return 0;
  if (x * 10 <= n && x * 10 + 1 <= n)
    return 2 + f(n, x * 10) + f(n, x * 10 + 1);
  if (x * 10 <= n) return 1 + f(n, x * 10);
  if (x * 10 + 1 <= n) return 1 + f(n, x * 10 + 1);
  return 0;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  long long t = 1;
  while (t--) {
    long long n, x = 1, ans = 0;
    cin >> n;
    if (n >= 1) ans++;
    ans += f(n, 1);
    cout << ans << "\n";
  }
}
