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;
int main() {
  long long n;
  cin >> n;
  long long x = n;
  vector<int> v;
  while (x) {
    v.push_back(x % 10);
    x = x / 10;
  }
  for (int i = v.size() - 1; i >= 0; i--) {
    if (v[i] == 1)
      v[i] = 1;
    else if (v[i] == 0)
      v[i] = 0;
    else {
      for (int j = i; j >= 0; j--) {
        v[j] = 1;
      }
      break;
    }
  }
  long long ans = 0;
  for (int i = v.size() - 1; i >= 0; i--) {
    ans = ans * 2 + v[i];
  }
  cout << ans;
  return 0;
}
