Problem: Olesya loves numbers consisting of n digits, and Rodion only likes numbers that are divisible by t. Find some number that satisfies both of them.

Your task is: given the n and t print an integer strictly larger than zero consisting of n digits that is divisible by t. If such number doesn't exist, print  - 1.

Input

The single line contains two numbers, n and t (1 ≤ n ≤ 100, 2 ≤ t ≤ 10) — the length of the number and the number it should be divisible by.

Output

Print one such positive number without leading zeroes, — the answer to the problem, or  - 1, if such number doesn't exist. If there are multiple possible answers, you are allowed to print any of them.

Examples

Input

3 2


Output

712

Solution (in JAVA):

Solution:
import java.util.Scanner;

public class main {

	public static void main(String[] args) {
		@SuppressWarnings("resource")
		Scanner input = new Scanner(System.in);
		int n = input.nextInt();
		String t = input.next();

		if (t.length() > n) {
			System.out.println("-1");
		} else {
			String res = "";
			if (n % 2 == 1 && t.equals("10")) {
				for (int i = 0; i < n - 1; i += t.length()) {

					res += t;

				}
				res = t.charAt(0) + res;

			} else {
				for (int i = 0; i < n; i += t.length()) {

					res += t;

				}
			}
			System.out.println(res);

		}

		input.close();

	}

}