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;

/**
 * @author stran
 * @version 1.0 (10/06/2016).
 */
public class P584A_OlesyaRodion {

    public static void main(String[] args) {
        Scanner scanner = new Scanner(System.in);
        int n = scanner.nextInt(),
            t = scanner.nextInt();

        if (n == 1 && t == 10) {
            System.out.println(-1);
            return;
        }

        StringBuilder builder = new StringBuilder("" + t);
        for (int i = (t == 10 ? 2 : 1); i < n; i++) {
            builder.append(0);
        }

        System.out.println(builder);
    }
}