import java.util.Arrays;
import java.util.Scanner;
public class Main{
	public static void main(String args[])throws Exception{
		Scanner sc=new Scanner(System.in);
		int are[]=new int[6];
		for(int i=0;i<are.length;i++)are[i]=sc.nextInt();
		Arrays.sort(are);
		double ave=0.0;
		for(int i=1;i<are.length-1;i++)ave+=are[i];
		ave/=4;
		System.out.printf("%.2f",ave);
	}
}