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) {
		Scanner sc = new Scanner(System.in);
		while (sc.hasNext()) {
			int n = sc.nextInt();
			int t = sc.nextInt();
			if (t == 10) {
				if (n == 1)
					System.out.println(-1);
				else {
					String anwser = t + "";

					for (int i = 0; i < n - 2; i++) {
						anwser += "0";
						
					}System.out.println(anwser);
				}
			} else {
				String anwser = t + "";
				for (int i = 0; i < n - 1; i++) {
					anwser += "0";
					
			}System.out.println(anwser);
			}

		}

	}
}