import java.math.BigDecimal;
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 * (double)B;
//		int ans = 50 * A + (int) (50 * A / d);
//		BigDecimal bdA = new BigDecimal(A);
//		BigDecimal bdB = new BigDecimal(B);
		BigDecimal bd = new BigDecimal(0.8);
		bd = bd.add(new BigDecimal((double) 0.2 * (double)B));
		BigDecimal a1 = new BigDecimal(50 * A);
		BigDecimal bd2, a2;
		bd2 = a1.divide(bd, 5, BigDecimal.ROUND_HALF_UP);
		a2 = bd2.setScale(1, BigDecimal.ROUND_DOWN);
		int a = a2.intValue();
		System.out.println(a + 50 * A);
	}
}