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

public class a{
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
		
        int a=sc.nextInt();
		int b=sc.nextInt();
		int c=sc.nextInt();
		int d=sc.nextInt();
		int e=sc.nextInt();
		int f=sc.nextInt();
		double score=0;
		
		int[] num = {a, b, c, d, e, f};
		
		Arrays.sort(num);
		
		for(int i=1; i<=4; i++){
			score+=num[i];
		}
		System.out.println(score/4);
    }
}