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;
string biner(long long x) {
  string s = "";
  while (x > 0) {
    s += x % 2 + '0';
    x /= 2;
  }
  reverse(s.begin(), s.end());
  return s;
}
int convertint(string s) {
  stringstream ss(s);
  long long a;
  ss >> a;
  return a;
}
int main() {
  long long n;
  while (scanf("%I64d", &n) == 1) {
    long long ans = 0;
    for (int i = 1; i < (1 << 10); i++) {
      string s = biner(i);
      long long a = convertint(s);
      if (a <= n) ans++;
    }
    printf("%I64d\n", ans);
  }
  return 0;
}
