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.io.IOException;
import java.util.*;


public class Main{

    public static void main (String args[]) throws IOException {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int k = sc.nextInt();
        String s = "";
        if(n < Integer.toString(k).length()){
            System.out.println("-1");
        }
        else if (k%10==0) {
            s = k+"";
            for (int i = 0; i < n-2; i++) {
                s+="0";
            }
        }
        else {
            for (int i = 0; i < n; i++) {
                s += k+"";
            }
        }
        System.out.println(s);
    }
}