using System;

public class Program

    {

        static void nhapchiso(out int a, out int b)

        {

            Console.WriteLine("nhap chieu dai");

            a = int.Parse(Console.ReadLine());//a = chieu dai//

            Console.WriteLine("nhap chieu rong");

            b = int.Parse(Console.ReadLine());//b= chieu rong//

        }

        static int chuvi(int a, int b)

        {

            return ((a + b) * 2);

        }

        static int dientich(int a, int b)

        {

            return (a * b);

        }

        static void nhaplaichiso(ref int a, ref int b)

        {

            Console.WriteLine("nhap lai chieu dai");

            a = int.Parse(Console.ReadLine());//a = chieu dai//

            Console.WriteLine("nhap lai chieu rong");

            b = int.Parse(Console.ReadLine());//b= chieu rong//

        }

        public static void Main(string[] args)

        {

            int a, b, P, S;

            nhapchiso(out a, out b);

            P = chuvi(a, b);

            Console.WriteLine("P = {0}", P);

            S = dientich(a, b);

            Console.WriteLine("S = {0}", S);

            nhaplaichiso(ref a, ref b);

            P = chuvi(a, b);

            Console.WriteLine("P = {0}", P);

            S = dientich(a, b);

            Console.WriteLine("S = {0}", S);

            Console.ReadLine();

        }

}

​

​

​