Object and Classes - Students 2.0 Error

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

namespace Objects_and_Classes
{
    class Program
    {
        static void Main(string[] args)
        {
            List<Student> students = new List<Student>();

            string input = Console.ReadLine();
            while (input != "end")
            {
                string[] tokens = input.Split(" ");
                string firstName = tokens[0];
                string lastName = tokens[1];
                int age = int.Parse(tokens[2]);
                string city = tokens[3];
                if (students.Count > 0)
                {
                    for (int i = 0; i < students.Count; i++)
                    {
                        if (firstName == students[i].FirstName && lastName == students[i].LastName)
                        {
                            students[students.Count - 1].Age = age;
                            students[students.Count - 1].Hometown = city;
                        }
                        else
                        {
                            Student student = new Student();
                            student.FirstName = firstName;
                            student.LastName = lastName;
                            student.Age = age;
                            student.Hometown = city;
                            students.Add(student);
                            input = Console.ReadLine();
                            break;
                        }
                    }
                }

                input = Console.ReadLine();
            }
            string cityEnd = Console.ReadLine();
            foreach (Student student in students)
            {
                if (cityEnd == student.Hometown)
                {
                    Console.WriteLine($"{student.FirstName} {student.LastName} is {student.Age} years old.");
                }
            }
        }
    }
}