import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int [] S = new int [6];
        for(int i=0; i<6; i++){
            S[i] = sc.nextInt();
        }
        Arrays.sort(S);
        int sum=0;
        for(int i=1; i<5; i++){
            sum = sum + S[i];
        }
        double r = sum/4.00;
        System.out.printf("%.2f\n",r);
    }
}