import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int A = scan.nextInt();
		int B = scan.nextInt();
		scan.close();
		double d = 0.8 + 0.2 * B;
		int ans = 50 * A + (int) (50 * A / d);
		System.out.println(ans);
	}
}