print("Введите число")
number = int(input())
newNumber = 0
temp = 0
temp2 = 0

temp = (number // 9)
temp2 = number - (temp * 9)

for item in range(temp):
    newNumber += 9 * item * 10

newNumber += temp2 * ((temp + 1) * 10)


print(newNumber)