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 s = "";
void s2(int a) {
  if (a == 0) {
    s += "0";
    return;
  }
  s2(a / 2);
  if (a - a / 2 * 2)
    s += "1";
  else
    s += "0";
  return;
}
int main() {
  int n;
  cin >> n;
  for (int i = 0; i < (int)513; i++) {
    s = "";
    s2(i);
    int k = atoi(s.c_str());
    if (k > n) {
      cout << i - 1;
      break;
    }
    if (k == n) {
      cout << i;
      break;
    }
  }
  return 0;
}
