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.math.BigInteger;
import java.util.Scanner;

public class Main {

	public static void main(String[] args)
	{
		
		Scanner scan =new Scanner(System.in);
		int n =scan.nextInt();
		int t= scan.nextInt();
		
		BigInteger x ;
		
		if(t==10 && n==1)
			System.out.println(-1);
		else
		{
			x =BigInteger.ONE;
			x= x.multiply(BigInteger.TEN.pow(n-1));
		
			
			if(x.remainder(BigInteger.valueOf(t))==BigInteger.ZERO )
				System.out.println(x);
			else
				System.out.println(x.multiply(BigInteger.valueOf(t)));
		}
		
			
	}
	
}