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.io.* ;
import java.util.* ;

public class Main
{
	public static void main(String[] args) 
	{
		Scanner s = new Scanner(System.in) ;
		int n = s.nextInt() ;
		int t = s.nextInt() ;
		if(n == 1 && t == 10)
			System.out.println(-1);
		else
		{
			String res = "" ;
			if(t == 10)
				res = "1" ;
			else
				res += t ;
			for(int i = 1 ; i < n ; i++)
				res += "0" ;
			System.out.println(res);
		}
	}
}