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 Sol {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int a = sc.nextInt();
        int b = sc.nextInt();
        StringBuffer sb = new StringBuffer();

        if (a == 1 && b == 10) {
            System.out.println(-1);
        } else {
            if (b <= 9) {
                for (int i = 0; i < a; i++) {
                    sb.append(b);
                }
            } else {

                for (int i = 0; i < a - 1; i++) {
                    sb.append(9);
                }
                sb.append(0);
            }
            System.out.println(sb);
        }

    }
}