01. Integer Operations

using System;

namespace IntegerOperations
{
    class Program
    {
        static void Main(string[] args)
        {
            int firstNum = int.Parse(Console.ReadLine());
            int secondNum = int.Parse(Console.ReadLine());
            int thurdNum = int.Parse(Console.ReadLine());
            int fourthNum = int.Parse(Console.ReadLine());
            int sum = (firstNum + secondNum) / thurdNum * fourthNum;
            Console.WriteLine(sum);
        }
    }
}