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.math.BigInteger;
import java.util.Scanner;

public class Main {


    public static void main(String[] args) {
       
      Scanner in=new Scanner(System.in);
      
      while(in.hasNext())
      {
         int n=in.nextInt();
         
         BigInteger t=new BigInteger(in.next());
         
         String s=new String();
         
         while(n!=0)
         {
             s+="9";
             n--;
         }
         
         BigInteger x=new BigInteger(s);
         
         boolean m=true;
         
         while(x.equals(new BigInteger("0"))==false)
         {
             if(x.mod(t).equals(new BigInteger("0")))
             {
                 System.out.println(x);
                 m=false;
                 break;
             }       
              
             else
                 x=x.subtract(new BigInteger("1"));
                     
         }
         
         if(m)
         {
             System.out.println(-1);
         }
        
      }
    }
}