import java.util.*;
import java.text.DecimalFormat;

public class Exercise151{
  public static void main (String[] args){

    Scanner sc = new Scanner(System.in);

    DecimalFormat df = new DecimalFormat("0.00");

    int[] judges = new int[6];
    for(int i = 0; i < 6; i++){
      judges[i] = sc.nextInt();
    }
    Arrays.sort(judges);
    int sum = 0;
    for(int i = 1; i < 5; i++){
      sum += judges[i];
    }
    System.out.println(df.format((double)sum / 4));
  }
}