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

namespace Profit
{
    class Program
    {
        static void Main(string[] args)
        {
            int r = int.Parse(Console.ReadLine());
            int s = int.Parse(Console.ReadLine());
            int c = int.Parse(Console.ReadLine());
            int maxQuantity = int.Parse(Console.ReadLine());

            double calculate = 0;
            double rasp = 1;
            double straw = 1;
            double cherr = 1;

            for (int i = 1; i <=r; i++)
            {

                for (int j = 1; j <=s; j++)
                {

                    for (int k = 1; k <=c; k++)
                    {

                        calculate = (i * 15) + j * (7.5)+(k*4.5);
                        if (calculate == maxQuantity - 1)
                        {
                            Console.WriteLine($"{calculate}");
                            return;
                        }
                        else if (calculate == maxQuantity)
                        {
                            Console.WriteLine(calculate);
                            return;
                        }
                    }
                }
            }
        }
    }
}