import java.util.Arrays;
import java.util.HashSet;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.Set;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		final int[] arr = new int[6];
		for(int i = 0; i < arr.length; i++){
			arr[i] = sc.nextInt();
		}
		
		final int sum = Arrays.stream(arr).sum();
		System.out.printf("%.2f\n", ((sum - Arrays.stream(arr).max().getAsInt() - Arrays.stream(arr).min().getAsInt()) / 4.0));
				
	}

}