#3)
s = 0
n = int(input())
for i in range(n):
    x = int(input())
    s += x
print(s / n)
#Ответ:4.2

#4)
n = int(input())
m = int(input())
a = []
for i in range(n):
    x = int(input())
    a.append(x)
print(a[m])
#Ответ: 32


#5)
n = int(input())
a = []
s = 0
for i in range(n):
    x = int(input())
    a.append(x)
    if i % 2 == 0:
        s += a[i]
print(s)