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;
long long mod = 1e9 + 7;
signed main() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  long long n;
  cin >> n;
  long long digits[9];
  memset(digits, 0, sizeof(digits));
  long long curdigit = 0;
  while (n) {
    digits[curdigit] = n % 10;
    n /= 10;
    curdigit++;
  }
  long long firstdigit = curdigit - 1;
  long long ans = 0;
  for (long long i = firstdigit; i >= 0; i--) {
    if (digits[i] > 1) {
      ans += pow(2, i + 1) - 1;
      break;
    } else if (digits[i] == 1) {
      ans += pow(2, i);
    }
  }
  cout << ans << "\n";
}
