package m.shin; import java.util.Scanner; public class Con445 { public static void main(String[] args) { Scanner s = new Scanner(System.in); int a = s.nextInt(); double b = s.nextDouble(); s.close(); double c = (50 * (double)a) / (0.8 + 0.2 * b); System.out.println(50 * a + (int)c); } }