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 numbers {


    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int i,j;
        i = in.nextByte();
        j = in.nextByte();
        String s;
        if (i==1 && j==10 ) System.out.println("-1");
        else {
            if (j==10) i--;
            s=Integer.toString(j);
            for (int z=1;z<i;z++){
                s+='0';
            }
            System.out.println(s);
        }
        in.close();
    }
}