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;
int32_t main() {
  ios_base::sync_with_stdio(false);
  cout << setprecision(10);
  vector<int> d;
  for (int i = 1; i < 1024; i++) {
    int x = i;
    int t = 1;
    int ans = 0;
    while (x) {
      ans += (x % 2) * t;
      x /= 2;
      t *= 10;
    }
    d.push_back(ans);
  }
  int n;
  cin >> n;
  for (int i = 0; i < d.size(); i++) {
    if (d[i] > n) {
      cout << i << endl;
      return 0;
    }
  }
}
