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;
import java.math.BigInteger;

public class A584
{
	public static void main(String[] args)
	{
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int t = scan.nextInt();

		if (t == 10 && n == 1)
		{
			System.out.println(-1);
		}
		else 
		{
			BigInteger multiple = new BigInteger(String.valueOf(t));	
			while (multiple.toString().length() != n)
			{
				multiple = multiple.multiply(BigInteger.TEN);
			}	
			System.out.println(multiple.toString());	
		}
	}
}