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;
using ll = long long int;
using ull = unsigned long long int;
int main() {
  ll a[1000], ind = 1;
  a[0] = 0;
  for (int i = 1; i <= 1000000000; i = i * 10) {
    int x = 0;
    while (a[x] < i) {
      a[ind] = i + a[x];
      ind++;
      x++;
      if (ind == 1000) break;
    }
    if (ind == 1000) break;
  }
  ll n, ans = 0;
  cin >> n;
  for (int i = 1; i < 1000; i++) {
    if (a[i] <= n)
      ans++;
    else
      break;
  }
  cout << ans;
  return 0;
}
