public static void CreateStudentsList(int count) { Console.WriteLine($"\nPlease, subscribe {count} students to courses. Format: <student name>//<course id>"); Regex pattern = new Regex(@"^[A-Za-z\-\s]+\/\/\d+$"); for (int i = 0; i < count; i++) { Console.Write("\nStudent " + (i + 1) + "\n"); var input = Console.ReadLine(); if (pattern.IsMatch(input)) { string[] studentsInfo = input.Split(new string[] { "//" }, StringSplitOptions.None); string sName = studentsInfo[0]; int courseId = int.TryParse(studentsInfo[1], out courseId) ? courseId : 0; try { if (Academy.Courses.Exists(c => c.Id == courseId)) { var studentId = Academy.AddStudent(sName); try { Academy.SignupStudentToCourse(studentId, courseId); } catch (AcademySignupException ae) { Console.WriteLine(ae.Message); if (ae.InnerException is CourseFullException || ae.InnerException is StudentIsBusyException) { i--; } } } else { Console.WriteLine("Enter a valid course id!"); i--; } } catch (PersonAgeException pe) { Console.WriteLine(pe.Message); i--; } catch (Exception ex) { Console.WriteLine(ex.Message); i--; } } else { Console.WriteLine("Wrong format! Please, try again."); i--; } } }