import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int A = sc.nextInt();
        int B = sc.nextInt();
        int c = 50*A;
        int d = 8+2*B;
        double e = 10*c/d;
        int f = c+(int)e;
        System.out.println(f);
    }
}