import java.util.Scanner;

public class Main {
	public static void main(String[] args) throws Exception {
		Scanner sc = new Scanner(System.in);
		int c = sc.nextInt();
		int y = sc.nextInt();
		sc.close();

		int a = y / 100;
		if (a < c) {
			System.out.println("can't exchange");
			return;
		}

		int b = a % 5;
		if (c <= b) {
			System.out.println("no exchange");
			return;
		}

		for (int x = c; ; x++) {
			if (x % 5 == b) {
				System.out.println(x);
				return;
			}
		}
	}
}