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.Objects;
import java.util.Scanner;
import java.util.stream.Collectors;
import java.util.stream.IntStream;

public class _584A
{
	public static void main(String... args)
	{
		Scanner in = new Scanner(System.in);
		int n = in.nextInt();
		int t = in.nextInt();
		int range = t == 10 ? n - 1 : n;
		int num = t == 10 ? 1 : t;
		String suf = t == 10 ? "0" : "";
		String collect = IntStream.range(0, range).mapToObj(i -> "" + num).collect(Collectors.joining("", "", suf));
		if (collect.length() > n)
		{
			System.out.println("-1");
		}
		else
		{
			if (Objects.equals(collect, "0"))
			{
				System.out.println("-1");
				return;
			}
			System.out.println(collect);
		}
	}
}