Mirko has thought of a top-secret natural number X that holds the secret of ruling the universe. His best friend Slavko is drunk with power and wants to get hold of that number. While searching Mirko's drawers late at night, Slavko found a slip of paper. It says that the sum of X and the mirror of X is exactly Y.
The mirror of X is formed by writing the decimal digits of X in reverse order. For example, the mirror of 123 is 321, and the mirror of 520 is 25.
For a given Y, compute how many natural numbers X satisfy this condition.