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.*;

public class Main {

    private final static Scanner sc = new Scanner(System.in);

    public static void main(String[] args) {

        int n = sc.nextInt();
        int t = sc.nextInt();

        int lenghtOfT = String.valueOf(t).toCharArray().length;
        if (lenghtOfT == n) {
            System.out.println(t);
            return;
        }

        if (lenghtOfT < n) {

            int howManyTimeMultiply10 = n - lenghtOfT;
            String newNumber = String.valueOf(t);
            for (int i = 0; i < howManyTimeMultiply10; i++){
                newNumber = newNumber + "0";
            }
            System.out.println(newNumber);
            return;
        }

        if (lenghtOfT > n) {

            System.out.println("-1");
            return;
        }

    }
}