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);
        String line1 = in.nextLine();
        String[] nt = line1.split(" ");
        int n = Integer.parseInt(nt[0]);
        int t = Integer.parseInt(nt[1]);
        String res = new String();
        if (t == 10 && n == 1)
        {
            res += -1;
        }
        else
        {
            if (t == 10)
            {
                int x = n;
                res += 1;
                while (x-- > 1)
                {
                    res += 0;
                }
            }
            else
            {
                while (n-- > 0)
                {
                    res += t;
                }
            }
        }
        System.out.println(res);
    }

}