#2022/6/14 13:40
n=int(input())
lis=list(map(int,input().split()))
sum1=0
sum2=0
count1=0
count2=0
for i in lis:
    if i>60:
        sum1=sum1+1
        count1=sum1*0.2
    elif i<=60:
        sum2=sum2+1
        count2=sum2*0.1
print(count1+count2)