06.ObjectsAndClasses-Students 2.0

06.ObjectsAndClasses-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

Hints
Check if the given student already exists.

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; }
    }
}