import java.util.Arrays;
import java.util.Scanner;

public class Main {
    public static void main(String[] args) {
        Scanner scan = new Scanner(System.in);
        int pointArray[] = new int[6];
        for (int i = 0; i < 6; i++) {
            pointArray[i] = scan.nextInt();
        }
        Arrays.sort(pointArray);
        double sum = 0.0;
        for (int i = 0; i < 5; i++) {
            if (i == 0) continue;
            sum += pointArray[i];
        }
        System.out.println(String.format("%.2f", sum / 4.0));
    }
}