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.util.Scanner;

public class MainClass {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int l , t;
        l = in.nextInt() ;
        t = in.nextInt() ;
        if (l == 1 && t!= 10) {
            System.out.println(t);
            return;
        }
        if (t == 10 && l == 1)
            System.out.println(-1);
        else if (t == 10 && l > 1)
        {
            System.out.print(1);
            for (int i = 0 ; i < l-1 ; i++)
                System.out.print(0);
        }
        else
            for (int i =0 ; i < l ; i++)
                System.out.print(t);


    }
}