def f(a,b):
    count = 0
    for i in range(a,b + 1):
        num = 0
        for j in str(i):
            num += int(j)
        if num % 5 == 0:
            count += 1
    return count


s = input()
lst = s.split(' ')
a = int(lst[0])
b = int(lst[1])

print(f(a,b))