// editor15
import java.util.*;
class Main{
    public static void main(String[]args){
        Scanner sc=new Scanner(System.in);
        try{
            String t=sc.next(),name=sc.next(),id=sc.next();
            int n=sc.nextInt(),sum=0;
            if(!t.equals("Undergraduate") &&! t.equals("Postgraduate"))
            { System.out.print("Invalid input"); return; }
            if(!sc.hasnextInt()){
                System.out.println("Invalid input");
            }
            //if(n<=0){
                //System.out.println("Invalid input");
            //}
            for(int i=0;i<n;i++){
                int g=sc.nextInt();
                if(g<-100||g>200){ System.out.print("Invalid input"); return; }
                sum+=g;
            }
            System.out.printf("%.2f",sum*1.0/n);
        }catch(Exception e){ System.out.println("Invalid input"); }
    }
}