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() {
  string s;
  int sz = (cin >> s, s.size()), cnt = 0;
  for (int i = 0; i < sz; i++)
    if (s[i] > '1') {
      for (int j = i; j < sz; j++) s[j] = '1';
      break;
    }
  while (sz > 1) {
    cnt += pow(2, sz - 1);
    s[0] = '0';
    while (s.size() > 1 && (s[0] == '0')) s.erase(0, 1);
    sz = s.size();
  }
  cnt += s == "0" ? 0 : 1;
  cout << cnt;
}
