import java.util.*;
public class Student
{
    public static void main(String[] args)
    {
        Scanner sc=new Scanner(System.in);
        try
        {
        String type=sc.nextLine();
        String name=sc.nextLine();
        int id=sc.nextInt();
        int n=sc.nextInt();
        int arr[]=new int[n];
        for(int i=0;i<n;i++)
        {
            arr[i]=sc.nextInt();
        }
        for(int i=0;i<n;i++)
        {
            if(arr[i]<0 || !(arr[i]>0 && arr[i]<100))
            {
                System.out.print("Invalid input");
                return;
            }
            
        }
        int sum=0;
        for(int x:arr)
        {
            sum=sum+x;
        }
        double avg=sum/n;
        System.out.printf(avg);
        }
        catch(Exception e)
        {
            System.out.print("Invalid input");
               return;
        }
    }
}