using System;
using System.Collections.Generic;
using System.Linq;

public class Yuki445
{
	public static void Main()
	{
		var x = Console.ReadLine()
				.Split(' ')
				.Select(n => int.Parse(n))
				.ToList();
		
		var ans = (int)(50 * x[0] / (0.8 + 0.2 * x[1]) + 0.000000001);
		ans += 50 * x[0];
		Console.WriteLine(ans);
		}
}