import java.util.Arrays;
import java.util.LinkedList;
import java.util.Scanner;
import java.util.TreeSet;

public class Main {
	
	public static long MOD = 1000000007;
	
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		
		final long N = sc.nextLong();
		final long K = sc.nextLong();
		
		final long upper = 500 * N;
		final long lower = 8 + 2 * K;
		
		System.out.println(50 * N + (upper / lower));
	}
}