import java.util.*;

public class Main {
    static int[][] prises;
    static int[][] dp;
	public static void main (String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int k = sc.nextInt();
		int value = 50 * n + (int)(500 * n / (8 + 2 * k));
		System.out.println(value);
	}
}