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;
void solve() {
  int n, x, c = 0, ans = 0;
  cin >> n;
  x = n;
  stack<int> s;
  while (x > 9) {
    s.push(x % 10);
    x /= 10;
  }
  s.push(x % 10);
  while (!s.empty()) {
    if (s.top() > 1) {
      ans += (1 << s.size());
      break;
    } else if (s.top() == 1) {
      ans += (1 << (s.size() - 1));
    }
    s.pop();
    if (s.empty()) ans++;
  }
  ans--;
  cout << ans;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(NULL);
  cout.tie(NULL);
  clock_t beg = clock();
  int t = 1;
  while (t--) solve();
  clock_t end = clock();
  fprintf(stderr, "%lf sec\n", (double)(end - beg) / (CLOCKS_PER_SEC));
  return 0;
}
