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>
#pragma optimize("Ofast")
using namespace std;
using ll = long long;
const int N = 1e5 + 5;
string s;
int ans = 0;
void solve(string t) {
  if (t > s && t.size() >= s.size()) return;
  ++ans;
  if (t.size() < s.size()) {
    solve(t + "0");
    solve(t + "1");
  }
}
int main() {
  ios_base::sync_with_stdio(0);
  cin >> s;
  solve("1");
  cout << ans << "\n";
  return 0;
}
