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