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:
//package CodeForces.Round324;

import java.util.Scanner;

/**
 * Created by Ilya Sergeev on 06.10.2015.
 */
public class Aolesia {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int n = sc.nextInt();
        int t = sc.nextInt();
        StringBuilder sb = new StringBuilder();
        if(t!= 10) {
            for (int i = 0; i < n; i++) {
                sb.append(t);
            }
            System.out.println(sb.toString());
        }
        else if(n>= 2){
            for (int i = 0; i < n-1; i++) {
                sb.append(1);
            }
            sb.append(0);
            System.out.println(sb.toString());
        }
        else System.out.println(-1);
    }
}