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.util.*;

public class olesya
{

    public static void main(String[] args)throws IOException
    {
        BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(br.readLine().trim());
        int n=Integer.parseInt(st.nextToken());
        int t=Integer.parseInt(st.nextToken());
        if(n>=4)
        {
            StringBuilder str=new StringBuilder("2520");
            for(int i=5;i<=n;i++)
                str.append("0");
            System.out.println(str);
        }
        else
        {
            int flag=-1;
            for(int i=(int)Math.pow(10,n-1);i<=(int)Math.pow(10,n)-1;i++)
                if(i%t==0)
                {
                    flag=0;
                    System.out.println(i);
                    break;
                }
            if(flag==-1)
                System.out.println(-1);
        }
    }
}