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 taxi  
{

	public static void main (String[] args) 
	{
		Scanner s = new Scanner(System.in) ;
		
		long x = s.nextInt() , y = s.nextInt() ;
		
		s.close();
		
		if (x==1 && y==10) System.out.println("-1");
		
		else if (y == 10)
		{
			System.out.print(10);
			
			for (int i = 3 ; i <=x  ;i++ ) System.out.print(0);
		}
		
		else 
		{
			
			for (int i = 1 ; i <=x  ;i++ ) System.out.print(y);
			
		}
						
		
		
		
		
		
		
	}
	
}