//Task1.py
continueInput = True
n = 0
sum = 0
while continueInput:
    currentNumber = int(input())
    if currentNumber%8==0 and currentNumber!=0:
        n+=1
        sum+=currentNumber
    continueInput = currentNumber!=0
if n==0:
    print("NO")
else:
    print(sum/n)

//Task2.py
continueInput = True
n = input()
i = len(n)-1
while i>=0:
    print(n[i], end='')
    i-=1

//Task3.py
continueInput = True
firstMax = 0
secondMax = 0
while continueInput:
    currentNumber = int(input())
    if currentNumber!=0:
        if currentNumber>secondMax:
            secondMax = currentNumber
        if (currentNumber>=firstMax):
            secondMax = firstMax
            firstMax = currentNumber
    continueInput = currentNumber!=0
print(secondMax)

//Task4.py
import math
p,q = [int(i) for i in input().split()]
i = 1
result = 0
continueSearch = True
while continueSearch:
    f = math.factorial(i)
    if f>=p and f<=q:
        result+=1
    i+=1
    continueSearch = f<q
print(result)