import java.math.BigInteger;
import java.util.*;
public class Main{
  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    System.out.println(new BigInteger(in.next(), 16).toString(10));
    in.close();
  }
}

import java.util.*;
public class Main{
  public static void main(String[] args) {
    Scanner in = new Scanner(System.in);
    String s = in.next();
    long result = 0;
    Map<Character, Integer> map = new HashMap<Character, Integer>();
    map.put('0', 0);map.put('1', 1);map.put('2', 2);map.put('3', 3);
    map.put('4', 4);map.put('5', 5);map.put('6', 6);map.put('7', 7);
    map.put('8', 8);map.put('9', 9);map.put('A', 10);map.put('B', 11);
    map.put('C', 12);map.put('D', 13);map.put('E', 14);map.put('F', 15);
    int len = s.length();
    for (int i = len-1, j = 0; i >= 0; --i, ++j) {
      result += map.get(s.charAt(i)) * (long)Math.pow(16, j);
    }
    System.out.println(result);
    in.close();
  }
}