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

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int []S = new int[6];
		for(int i = 0; i < 6; i++) {
			S[i] = scan.nextInt();
		}
		scan.close();
		Arrays.sort(S);
		int sum = 0;
		for(int i = 1; i < 5; i++) {
			sum += S[i];
		}
		double ans = (double)sum / 4;

		ans = Math.round(ans * 100) / 100.0;
		System.out.printf("%.2f", ans);
		System.out.println();
	}
}