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 P584A
{
	public static void main(String[] args)
	{
		Scanner scan = new Scanner(System.in);
		int length = scan.nextInt();
		int div = scan.nextInt();
		String str = String.valueOf(div);
		if (length < str.length())
		{
			System.out.println(-1);
			return;
		}
		if (div == 10)
			div = 1;
		StringBuilder num = new StringBuilder(String.valueOf(div));
		for (int i = 1; i < length; i++)
			num.append("0");
		System.out.println(num);

		scan.close();
	}		
}