Print the key mappings for old Nokia mobile keys combination

[kushsharma1001]

Problem Statement: Print the key mapping permutations for old Nokia mobile keys combination.

Input: 1
Output: abc
Explanation: Key '1' on old Nokia keypad corresponds to abc

Input: 21
Output: da db dc ea eb ec fa fb fc
Explanation: Pressing key '2' and then key '1' on old Nokia keypad gives permutations of da db dc ea eb ec fa fb fc

[siriak]

We don't need that, thanks