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;

/**
 * Created by FoLinc on 10.12.2017.
 */
public class _584A {
    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);

        int
                n = scanner.nextInt(),
                t = scanner.nextInt();

        int size = Integer.toString(t).length();
        if (n < size) {
            System.out.println(-1);
            return;
        }


        System.out.print(t);
        for (; n - size > 0; n--) {
            System.out.print(0);
        }
    }
}