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Problems

# 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 (0n9).

#### Output

Print the required amount of two-digit numbers.

Time limit 1 second
Memory limit 128 MiB
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.

Source ІІ stage of All-Ukrainian Olympiad, Zhytomyr region