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.text.ParseException;
import java.text.SimpleDateFormat;
import java.util.*;

/**
 * Created by Юлия on 19.07.2016.
 */
public class hello {
    public static void main(String[] args) {
        int n, t;
        Scanner input = new Scanner(System.in);
        n = input.nextInt();
        t = input.nextInt();
        StringBuilder s = new StringBuilder();
        s.setLength(n);
        if (t == 10 && n == 1){
            System.out.println(-1);
            return;
        }
        if (t == 10) {
            for (int i = 0; i < n - 1; i++)
                s.setCharAt(i, '1');
            s.setCharAt(n - 1, '0');
        } else
        for (int i = 0; i < n; i++)
            s.setCharAt(i,(char) (t + (int)'0'));

        System.out.println(s);

    }
}