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.io.*;
import java.math.BigInteger;
import java.util.*;

public class Main {
    public static int distance(int x1,int y1,int x2,int y2){
        return (Math.abs(x1-x2)+Math.abs(y1-y2));
    }
    public static void main(String[] args) throws IOException {
    // TODO Auto-generated method stub
       
        Scanner sc = new Scanner(System.in);
        int n ,t;
        n= sc.nextInt();
        t= sc.nextInt();
        if(n == 1)
        {
               if(t>9)
            {
                System.out.println(-1);
                return ;
            }
            System.out.println(t);
            return ;
        }
        else 
        {
         BigInteger x;
         x= new BigInteger("1");
         while (--n != 0)
         {
             x= x.multiply(BigInteger.valueOf(10));
         }
        
        while(true)
        {

            if(x.mod(BigInteger.valueOf(t)).equals(BigInteger.ZERO))
            {
                System.out.println(x);
                return;
               }
            x = x.add(BigInteger.valueOf(1));
            
                
        }
    }
    

    }
}