using System;

public class Program

{

    public static void Main()

    {

    Console.WriteLine("Start algoritm");

        int A = 0;

        int B = 0;

        do

        {

            Console.WriteLine("Input a = ");

            A = Convert.ToInt32(Console.ReadLine());

            if(A <= 0)

            {

                Console.WriteLine("Value A cannot be less than 0");

            }

            Console.WriteLine("Input b = ");

            B = Convert.ToInt32(Console.ReadLine());

            if(B <= 0)

            {

                Console.WriteLine("Value B cannot be less than 0");

            }

        }

        while(A <= 0 || B <= 0);

        int S = A + B;

        Console.WriteLine("Square = " + S);

        Console.WriteLine("Stop algoritm");

    }

}