After starting the program, a menu appears and you should enter one of the numbers (0-6):
1) Today's tasks - shows today's tasks.
2) Week's tasks - shows the tasks to be performed in the next 7 days.
3) All tasks - shows all tasks stored in the database.
4) Missed tasks - shows tasks that are older than today's date.
5) Add task - to add a task, enter its name and deadline. Date must be entered in YYYY-MM-DD format.
6) Delete task - shows the list of tasks, you should enter the number of the task you want to delete.
0) Exit - exit from the program.