using System;
using System.Collections.Generic;
using System.Linq;
using System.Text;
using System.Threading.Tasks;

namespace _19.Thea_The_Photographer
{
    class Program
    {
        static void Main(string[] args)
        {
            double pictureNumber = double.Parse(Console.ReadLine());
            double filterTime = double.Parse(Console.ReadLine());
            double filterFactor = double.Parse(Console.ReadLine());
            double uploadTime = double.Parse(Console.ReadLine());

            //Find out the good pictures!

            var usefulPictures = (Math.Ceiling(filterFactor * pictureNumber)) / 100.0;

            //Find out filter time!

            var filteredPicturesTime = (pictureNumber * filterTime);


            //Find out upload time!

            var finalUploadTime = (usefulPictures * uploadTime);

            //turn total time seconds into final time!

            var totalTime = (finalUploadTime + filteredPicturesTime);


            TimeSpan time = TimeSpan.FromSeconds(totalTime);


            string str = time.ToString(@"d\:hh\:mm\:ss");


            Console.WriteLine(time);



        }
    }
}