using System;
using System.Collections;
using System.Collections.Generic;
using System.Collections.Specialized;
using System.Text;
using System.Text.RegularExpressions;
using System.Linq;

public class Magatro
{
    static int A, B;
    static void Main()
    {
        string[] s = Console.ReadLine().Split(' ');
        A = int.Parse(s[0]);
        B = int.Parse(s[1]);
        Console.WriteLine(F(A, B));
    }
   static int F(int N,int K)
    {
        return 50 * N + floor(N, K);
    }
    static int floor(int N,int K)
    {
        double bo = 50.0 * (double)N;
        float si = 0.8f + 0.2f * K;
        return (int)(bo/si);
    }
}