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;
string DecToBin(long long number) {
  if (number == 0) return "0";
  if (number == 1) return "1";
  if (number % 2 == 0)
    return DecToBin(number / 2) + "0";
  else
    return DecToBin(number / 2) + "1";
}
int main() {
  long long n, ans = 0, p;
  cin >> n;
  for (int i = 1; i <= 1024; i++) {
    stringstream ss;
    ss << DecToBin(i);
    ss >> p;
    if (p <= n) ans++;
  }
  cout << ans;
  return 0;
}
