using System;

public class Program

{

    class Customer

    {

        public int Age { get; set; }

        public string Email { get; set; }

        public string VatNumber { get; set; }

        public string FirstName { get; set; }

        public string LastName { get; set; }

        public string GetFullName()

        {

            return $"{FirstName} {LastName}";

        }

​

        public bool FindByLastName(string lastname)

        {

            if(lastname == LastName)

            {

                return true;

​

            }

            else

            {

                return false;

            }

        }

​

    }

​

        static void Main(string[] args)

        {

            var customers = new Customer[5] {

                new Customer() {

                    Age = 15,

                    FirstName = "15",

                    LastName = "15"

                },

                new Customer() {

                    Age = 16,

                    FirstName = "16",

                    LastName = "5"

                },

                new Customer() {

                    Age = 25,

                    FirstName = "25",

                    LastName = "25"

                },

                new Customer() {

                    Age = 37,

                    FirstName = "37",

                    LastName = "37"

                },

                new Customer() {

                    Age = 55,

                    FirstName = "55",

                    LastName = "55"

                },

            };

​

            var length = NameNum(customers);

            //Console.WriteLine(length);

​

            var newCustomers = new Customer[5];

            for (var i = 0; i < customers.Length; i++)

            {var j = 0;

                if (customers[i].LastName.Equals(NameNum(customers)))

                {

​

                    newCustomers[j] = customers[i];

                    Console.WriteLine(newCustomers[j].GetFullName());

                    j++;

                    Array.Resize<Customer>(ref newCustomers, j);

                }

                //Array.Resize<Customer>(ref newCustomers, j);

            }

​

            //Array.Resize<Customer>(ref newCustomers,);

​

            //foreach (var i in newCustomers)

            //{

​

​

            //    Console.WriteLine(i.GetFullName());

​

​

            //}

​

        }

​

        public static string NameNum(Customer[] arr)

        {

            foreach (var customer in arr)

            {

                //var isvalid = 0;

                if (customer.FindByLastName("55"))

                {

                    //Console.WriteLine(customer.GetFullName());

                    return customer.LastName;

                }

            }

            return null;

        }