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 int pow_mod(long long int a, long long int b) {
  long long int res = 1;
  while (b) {
    if (b & 1) res = (res * a);
    a = (a * a);
    b >>= 1;
  }
  return res;
}
int main() {
  ios_base::sync_with_stdio(0);
  long long int n;
  cin >> n;
  long long int num[11];
  int k = 0;
  while (n) {
    num[k] = n % 10;
    n = n / 10;
    k++;
  }
  long long int ans = 0, f = 0;
  for (int i = k - 1; i >= 0; i--) {
    if (num[i]) {
      ans += pow_mod(2, i);
      if (num[i] > 1) f = 1;
    } else if (num[i] == 0 && f == 1) {
      ans += pow_mod(2, i);
    }
  }
  cout << ans << "\n";
  return 0;
}
