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

}