import java.util.Scanner;

class Question445
{
	public static void main(String[] str)
	{
	
		Scanner scan = new Scanner(System.in);
		
		int     n = scan.nextInt();
		double  k = scan.nextDouble();
		

		System.out.println((int)(50*n+((50*n)/(0.8+(0.2*k)))));
	}
}