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 MAX = 101010;
set<long long> st;
void bt(long long x) {
  if (x > 2000000000) return;
  st.insert(x);
  bt(x * 10ll);
  bt(x * 10ll + 1ll);
}
int main() {
  ios::sync_with_stdio(0);
  bt(1ll);
  long long n;
  cin >> n;
  int ans = 0;
  for (auto i : st) {
    ans++;
    if (i > n) {
      cout << ans - 1 << endl;
      return 0;
    }
  }
  return 0;
}
