using System;
using System.Linq;

namespace _445
{
    class Program
    {
        static void Main(string[] args)
        {
            double[] x = Console.ReadLine().Split().Select(double.Parse).ToArray();
            Console.WriteLine(50 * x[0] + Math.Floor((250 * x[0]) / ((4 + x[1]))));
        }
    }
}