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;
map<long long int, long long int> m;
vector<long long int> v;
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long int n;
  cin >> n;
  long long int c = 0;
  for (long long int i = 1; i <= 512; i++) {
    string s;
    long long int x = i;
    while (x != 0) {
      long long int rem = x % 2;
      s.push_back((char)(rem + 48));
      x = x / 2;
    }
    reverse(s.begin(), s.end());
    long long int num = stoi(s);
    if (num <= n) c++;
  }
  cout << c << endl;
  return 0;
}
