import java.util.*;

public class Main {
	static Scanner sc = new Scanner(System.in);
	public static void main(String[] args) {
		double n = sc.nextDouble();
		double k = sc.nextDouble();
		double score = 50*n;
		double a = 0.8;
		double b = 0.2;
		double sub_score = (score)/(a+b*k);
		int total_score = (int)score + (int)sub_score;
		System.out.println(total_score);
	}
}