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, x, y, i, c = 0;
  cin >> n;
  string s = "", t;
  x = n;
  while (x > 0) {
    s = char(x % 10 + 48) + s;
    x /= 10;
  }
  t = s;
  y = s.length();
  s[0] = min(s[0], '1');
  for (i = 1; i < y; i++) {
    if (t[i - 1] > '1') {
      s[i] = '1';
      t[i] = t[i - 1];
    } else {
      s[i] = min(s[i], '1');
    }
  }
  long long sm = 0;
  for (i = 0; i < y; i++) {
    if (s[i] == '1') {
      sm = sm + pow(2, y - i - 1);
    }
  }
  cout << sm;
}
