looper = int(input())
if (looper>0 and looper<=100):
    input=input()
    list = str.split(input)

    for i in range(len(list)):
        list[i]=int(list[i])

    list=sorted(set(list))
    sum=counter=0

    for i in range(len(list)):
        sum = sum+list[i]
        counter=counter+1
    print(sum/counter)