import java.util.Scanner;
public class Main{
public static void main(String[] agrs){
Scanner in = new Scanner(System.in);
String s = in.nextLine().substring(2);
int sum = 0,count=0;
for(int i= s.length()-1;i>=0;i--){
char c = s.charAt(i);
if(c<='9'){
sum += (s.charAt(i)-'0')*Math.pow(16,count);
}else{
sum += (s.charAt(i)-'7')*Math.pow(16,count);
}
count++;
}
System.out.println(sum);
}
}
public class Main{
public static void main(String[] agrs){
Scanner in = new Scanner(System.in);
String s = in.nextLine().substring(2);
int sum = 0,count=0;
for(int i= s.length()-1;i>=0;i--){
char c = s.charAt(i);
if(c<='9'){
sum += (s.charAt(i)-'0')*Math.pow(16,count);
}else{
sum += (s.charAt(i)-'7')*Math.pow(16,count);
}
count++;
}
System.out.println(sum);
}
}