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 Main{
    public static void main(String [] args)
    {
        Scanner scan=new Scanner(System.in);
        int n=scan.nextInt();
        int t=scan.nextInt();
        String s=Integer.toString(t);
       
        while(s.length()<n)
        {
            s=s+"0";
        }
        if(s.length()==n)
            System.out.println(s);
        else
            System.out.println("-1");
    }
}