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 Solution {

    public static void main(String[] args) throws IOException
    {
        BufferedReader br =new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st =new StringTokenizer(br.readLine());
        int n=Integer.parseInt(st.nextToken());
        int t=Integer.parseInt(st.nextToken());
        PrintWriter out =new PrintWriter(System.out);
        if(t==10 )
        {
            if(n==1){out.println(-1);}
            else 
            {
                out.print(1);
                for(int i=1;i<n;i++)out.print(0);
            }
        }
        else
        {
            for(int i=0;i<n;i++)out.print(t);
        }
        out.close();
    }
   
}