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;
signed main() {
  std::ios::sync_with_stdio(0);
  cin.tie(0);
  ;
  long long n, d = 1;
  cin >> n;
  vector<long long> v;
  v.push_back(0);
  v.push_back(1);
  while (d < 1e9) {
    long long c = v.size();
    d *= 10;
    for (long long i = 0; i < c; i++) {
      v.push_back(v[i] + d);
    }
  }
  v.push_back(1e9);
  long long ct = 0;
  for (long long i = 1; i < v.size(); i++) {
    if (v[i] <= n)
      ct++;
    else
      break;
  }
  cout << ct;
}
