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 Main{

    static Scanner input = new Scanner(System.in);

    public static void main(String[] args) {
        int n, t;

        n = input.nextInt();
        t = input.nextInt();

        if (n == 1 && t == 10) {
            System.out.println(-1);
        } else if (t != 10) {
            for (int i = 0; i < n; i++) {
                System.out.print(t);
            }
        } else {
            System.out.print(1);
        
        for (int i = 0; i < n - 1; i++) 
            System.out.print(0);
       
        }
    }

}