06.ObjectAndClasses-Students 2.0

06. Students 2.0
Use the class from the previous problem. If you receive a student, which already exists (first name and last name should be unique) overwrite the information.
Input                              Output
John Smith 15 Sofia                John Smith is 15 years old.
Peter Ivanov 14 Plovdiv            Linda Bridge is 27 years old.
Peter Ivanov 25 Plovdiv
Linda Bridge 16 Sofia
Linda Bridge 27 Sofia
Simon Stone 12 Varna
end
Sofia

Anthony Taylor 15 Chicago          Anthony Taylor is 15 years old.
David Anderson 16 Washington       Jack Lewis is 26 years old.
Jack Lewis 14 Chicago              David Lee is 18 years old.
David Lee 14 Chicago
Jack Lewis 26 Chicago
David Lee 18 Chicago
end
Chicago


using System;
using System.Collections.Generic;
using System.Linq;

namespace Students
{
    class Program
    {
        static void Main(string[] args)
        {
            string command = "";
            var students = new List<Student>();
            while ((command = Console.ReadLine()) != "end")
            {
                string[] array = command.Split();
                string firstName = array[0];
                string lastName = array[1];
                int age = int.Parse(array[2]);
                string city = array[3];

                if (IsStudentExisting(students, firstName, lastName))
                {

                    var student = GetStudent(students, firstName, lastName, age);
                }
                else
                {
                    var student = new Student()
                    {
                        FirstName = firstName,
                        LastName = lastName,
                        Age = age,
                        City = city,

                    };
                    students.Add(student);
                }
            }
            string filterCity = Console.ReadLine();
            var filteredStudents = students.Where(s => s.City == filterCity).ToList();

            foreach (Student student in filteredStudents)
            {

                Console.WriteLine($"{student.FirstName} {student.LastName} is {student.Age} years old.");
            }
        }

        static bool IsStudentExisting(List<Student> students, string firstName, string lastName)
        {
            foreach (Student student in students)
            {
                if (student.FirstName == firstName && student.LastName == lastName)
                {
                    return true;
                }
            }
            return false;
        }

        static Student GetStudent(List<Student> students, string firstName, string lastName, int age)
        {
            Student existingStudent = null;
            foreach (Student student in students)
            {
                if (student.FirstName == firstName && student.LastName == lastName)
                {
                    existingStudent = student;
                    existingStudent.Age = age;
                }
            }
            return existingStudent;
        }
    }
    class Student
    {
        public string FirstName { get; set; }
        public string LastName { get; set; }
        public int Age { get; set; }
        public string City { get; set; }
    }
}