package no445;

import java.util.Scanner;

public class Main {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		long n = sc.nextLong();
		long k = sc.nextLong();
		long score = 50 * n + (500 * n / (8 + 2 * k));
		System.out.println(score);
	}

}