In day 2 you were given a set of rules to be parsed first. The looked like this:
1-3 a: abcde 1-3 b: cdefg 2-9 c: ccccccccc
Each line contains two numbers, a character and a password
In part 1 you have to check if the given character appears at least and at most times given by the numbers. Each password that matches this behavior is considered valid.
In part 2 you need to check if the given character is on one of the two given positions indicated by the numbers.