import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int[] arr = new int[6];
        for (int i = 0; i < 6; i++) {
            arr[i] = sc.nextInt();
        }
        Arrays.sort(arr);
        int sum = 0;
        for (int i = 1; i < 5; i++) {
            sum += arr[i];
        }
        System.out.println(new java.text.DecimalFormat("#0.00").format(sum / 4.0));
    }
}