学步园

import java.util.Scanner;
public class Main {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        String s = in.next();
        in.close();
        int[] a = new int[s.length()];
        char[] b = s.toCharArray();
        int t = 0;
        for (int i = 0; i < s.length(); ++i) {
            t = b[i] - 48;
            a[i] = (t > 9) ? b[i] - 55 : t;
        }
        long sum = 0;
        for (int j = a.length - 1; j >= 0; --j) {
            sum += (long) (a[j] *  Math.pow(16, a.length - j - 1));
        }
        System.out.println(sum);
    }
}