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 gcd(long long a, long long b) {
  if (a == 0) return b;
  return gcd(b % a, a);
}
long long powm(long long base, long long exp, long long mod = 10000000079) {
  base %= mod;
  long long ans = 1;
  while (exp) {
    if (exp & 1LL) ans = (ans * base) % mod;
    exp >>= 1LL, base = (base * base) % mod;
  }
  return ans;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  long long t = 100;
  string n;
  cin >> n;
  long long ans = 0, flag = 0;
  for (int i = 0; i < n.length(); i++) {
    if (n[i] == '1') {
      ans += powm(2, n.length() - 1 - i);
    } else if (n[i] > '1') {
      ans += powm(2, n.length() - i);
      flag = 1;
      break;
    }
  }
  if (flag) ans--;
  cout << ans << '\n';
}
