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>
const int INF = (int)1e9;
using namespace std;
string str;
bool valid(string a) {
  if (a.size() > str.size() || (a.size() == str.size() && a > str))
    return false;
  return true;
}
int solve(string a) {
  if (a.size() >= str.size() && a >= str) return 0;
  int res = 0;
  if (valid(a + '1')) res += solve(a + '1') + 1;
  if (valid(a + '0')) res += solve(a + '0') + 1;
  return res;
}
int main() {
  ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
  cin >> str;
  cout << solve("1") + 1 << '\n';
  return 0;
}
