import java.util.*;

public class Main {
    private static Scanner sc = new Scanner(System.in);
    public static void main(String[] args) throws Exception {
        List<Float> list = new ArrayList<>();
        for (int i = 0;i < 6;i++) {
            list.add(sc.nextFloat());
        }
        
        Collections.sort(list);
        
        float ret = 0;
        for (int i = 1;i < 5;i++) {
            ret += list.get(i);
        }
        
        Formatter fm = new Formatter();
        fm.format("%.2f", ret/4);
        System.out.println(fm);
    }
}