namespace CalculatorApp
{
    public interface ICalculator
    {
        int Add(int firstValue, int secondValue);
        int Subtract(int firstValue, int secondValue);
        int Multiply(int firstValue, int secondValue);
        int Divide(int firstValue, int secondValue);
    }

    public abstract class BaseCalculator : ICalculator
    {
        public virtual int Add(int firstValue, int secondValue)
        {
            return firstValue + secondValue;
        }

        public virtual int Subtract(int firstValue, int secondValue)
        {
            return firstValue - secondValue;
        }

        public virtual int Multiply(int firstValue, int secondValue)
        {
            return firstValue * secondValue;
        }

        public virtual int Divide(int firstValue, int secondValue)
        {
            return firstValue / secondValue;
        }
    }

    public class CalculatorAgent : BaseCalculator
    {
        public override int Add(int firstValue, int secondValue)
        {
            return base.Add(firstValue, secondValue);
        }

        public override int Subtract(int firstValue, int secondValue)
        {
            return base.Subtract(firstValue, secondValue);
        }

        public override int Multiply(int firstValue, int secondValue)
        {
            return base.Multiply(firstValue, secondValue);
        }

        public override int Divide(int firstValue, int secondValue)
        {
            return base.Divide(firstValue, secondValue);
        }
    }
}