Because you can flip a tile, two tiles match if the number on the left or right matches the left or right on the other tile. For example, the domino $2|1$ maches the domino $1|3$ without flipping either, and $2|1$ matches $2|3$ after flipping the first domino.

You should print all matches. First check a direct match, then try flipping tiles. But don$$t flip a tile whose left and right numbers are the same. If there is no match, print $"$No match".

Don't restructure the code. Fill in a condition for each of the if $(/*$ Your code goes here $*/)$ statements.