NewMonth creates a new Month.

NewSolver creates a new Solver for a specific day and part.

Part1 means we want to solve part 1.

Part2 means we want to solve part 2.

PartAll means we want to solve both part 1 and part 2.

InputParseError occurs when something is not implemented.

Month manages daily solvers.

NoInputError occurs when we have no input values.

NoSolutionError occurs when we are unable to find a solution.

NotImplementedError occurs when something is not implemented.

Solver is the main solver.

UnkownDayError occurs when given day is not defined.

UnkownPartError occurs when given part is not defined.

Day is the interface for daily solutions.