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 codeforces
{
	public static void main(String ar[])
	{
		Scanner ob=new Scanner(System.in);
		int n=ob.nextInt();
		int t=ob.nextInt();
		if(t==10)
		{
			if(n==1) System.out.println(-1);
			else
			{
				for(int i=0;i<n-1;i++) System.out.print(1);
				System.out.println(0);
			}

		}
		else
		{
			for(int i=0;i<n;i++)
				System.out.print(t);
		}
	}
}