import java.util.Scanner;

public class b {
	public static void main(String args[]){
		Scanner sc = new Scanner(System.in);
		int max = -1;
		int min = -1;
		double sum = 0;
		for(int i = 0; i < 6; i++){
			int foo = sc.nextInt();
			if(max == -1 || foo > max)
				max = foo;
			if(min == -1 || foo < min)
				min = foo;
			sum += foo;
		}
		System.out.printf("%.2f\n", (sum - max - min) / 4);
	}
}