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>
#pragma GCC optimize(2)
using namespace std;
int n, a, cnt;
string s;
void binary(int x) {
  if (x / 2 > 0) binary(x / 2);
  s += char(x % 2 + '0');
}
int main() {
  ios::sync_with_stdio(0);
  scanf("%d", &n);
  for (int i = 1;; i++) {
    s = "";
    binary(i);
    stringstream ss;
    ss << s;
    ss >> a;
    if (a <= n)
      cnt++;
    else
      break;
  }
  printf("%d", cnt);
}
