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.Scanner;
public class test{

  public static void main(String[] args) 
  {
	  
	  Scanner a=new Scanner(System.in);
	  int x=a.nextInt();
	  int t=a.nextInt();
	  String ch=new String();
	  ch=ch+ Integer.toString(t);
	  while(ch.length()<x) ch=ch+'0';
	  String ch1=Integer.toString(t);
	
	 if(ch1.length()>x ) System.out.println("-1");
	 else System.out.println(ch);
	  
  }
  
	 
	 }