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 rodion
{
  public static void main(String[] args)
  {
    Scanner in=new Scanner(System.in);
    int n=in.nextInt();
    int t=in.nextInt();   
    String s="";
    if(t<10)
    {
      for(int i=0;i<n;i++)
        s=s+""+t;
    }
    else
    {              
      for(int i=0;i<n;i++)
      {
        if(i+1==n)
          s=s+""+0;
        else
          s=s+""+1;
      }
    }
    if((n==1&&s.length()>1)||(n==1&&t==10))
      System.out.println("-1");
    else
      System.out.println(s);
  }
  //so hard much wow
}