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 final class Codechef {
    public static void main (String[] args) {
        Scanner sc= new Scanner(System.in);
        int n=sc.nextInt(),t=sc.nextInt(),a=1;
        if (n == 1 && t == 10)
            System.out.println("-1");
        else {
            System.out.print(t);
            if (t == 10) a++;
            for (a=a; a < n; a++)
                System.out.print("0");
        }
    }
}