def digit_sum(number):
    return sum(map(int, list(str(number)))) % 2


def calculate_little(begin, end):
    result = 0
    for number in range(begin, end + 1):
        if digit_sum(number):
            result += 1
    return result


result = 0
begin, end = int(input()), int(input())
if end - begin < 1000 or True:
    print(calculate_little(begin, end))
else:
    fill = []
    old_begin, old_end = begin, end
    while begin % 10 != 1:
        fill.append(begin)
        begin += 1
    while end % 10 != 0:
        fill.append(end)
        end -= 1
    print(fill, begin, end)
    print((end - begin) // 2 + sum(map(digit_sum, fill)) + (old_end - old_begin) // 10 % 2)