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

	    	{
	    		System.out.print(t);
	    	}
	    }
	   }

}