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 name
{
      public static void main(String[]args)throws IOException
      {
            Scanner sc=new Scanner(System.in);
            int n=sc.nextInt();
            String t=sc.next();
            while(t.length()<n)
            {
                  t+="0";
            }
            if(t.length()==n)
            System.out.println(t);
            else
            System.out.println("-1");
      }
}