# coding:UTF-8
answer = 0
month = 1

def seachHD(month, daysOfMonth):
    day = 1
    while day <= daysOfMonth:
        daySum = int(day / 10) + (day % 10)
        if daySum == month:
            global answer
            answer += 1
        day += 1

while month <= 12:
    if month == 2:
        seachHD(month, 28)
    elif month == 4 or month == 6 or month == 9 or month == 11:
        seachHD(month, 30)
    else:
        seachHD(month, 31)
    month += 1

print(answer)