integer operations

using System;
using System.Linq;
using System.Text;
using System.Globalization;
using System.Numerics;
using System.Collections;

namespace whileloop
{
    class Program
    {
        static void Main()
        {
            int number1 = int.Parse(Console.ReadLine());
            int number2 = int.Parse(Console.ReadLine());
            int number3 = int.Parse(Console.ReadLine());
            int number4 = int.Parse(Console.ReadLine());

            int sum = ((number1 + number2) / number3) * number4;

            Console.WriteLine(sum);

        }
    }
}