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 problem1 {
    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        long n = in.nextLong();
        long k = in.nextLong();
        qanak_bajanarar(n, k);
    }

    static void qanak_bajanarar(long n, long k) {
        String str = k + "";
        if (n == 1 & k == 10) {
            System.out.println(-1);
        } else {
            for (int i = 0; i < n - (k + "").length(); i++) {
                str += 0;
            }
            System.out.println(str);
        }

    }
}