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 coA
{
 public static void main(String args[])
 {
  int n,t;
  Scanner in=new Scanner(System.in);
  n=in.nextInt();
  t=in.nextInt();
  if((n==1)&&(t==10))
  {
    System.out.println("-1");
    return;
  } 
 
  if(t==10 && n!=1)
      if(n%2==0)
        n=n/2;
      else
        { n=n/2;
          System.out.print("1");  
        }
      
    for(int i=1;i<=n;i++)
    {
    System.out.print(t);
    }
}
}