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.*;
public class Rodian
{
	public static void main(String []args)
	{
	Scanner sc=new Scanner(System.in);
	int n,t;
	n=sc.nextInt();
	t=sc.nextInt();
	if(t==10)
	{
		if(n==1)
		{
			System.out.println("-1");
		}
		else
		{
			for(int i=1;i<n;i++)
			{
				System.out.print("1");
			}
			System.out.print("0");
			
		}
	}
	else
	{
		for(int j=1;j<=n;j++)
		{
			System.out.print(t);
		}
	}

	}
}