import java.util.*;

class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		
		double sum = 0;
		int[] ar = new int[6];
		for (int i=0; i<6; i++) ar[i] = sc.nextInt();
		Arrays.sort(ar);
		for (int i=1; i<5; i++) sum += ar[i];
		System.out.println(String.format("%.2f",sum/4));
		
		
	}
}