Problems
Constant sum of digits
Constant sum of digits
Find the amount of two-digit numbers that do not change their sum of digits when multiplying a number by a single-digit integer n (n = 0 .. 9).
Input
One integer n (0 ≤ n ≤ 9).
Output
Print the required amount of two-digit numbers.
Input example #1
2
Output example #1
10
Example description: When multiplying two-digit numbers by 2, the following numbers do not change the sum of the digits: 18 27 36 45 54 63 72 81 90 99.