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:
/*
 * To change this license header, choose License Headers in Project Properties.
 * To change this template file, choose Tools | Templates
 * and open the template in the editor.
 */


//package javaapplication2;

import java.util.Scanner;

/**
 *
 * @author MOSTAFA
 */
public class JavaApplication2 {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) {
       Scanner x =new Scanner(System.in);
      int n;
      String s;
      n = x.nextInt();
      s=x.next();
        if (n<s.length()) {
            
             System.out.print(-1);
        }
        else
        {
            System.out.print(s);
        for (int i = 0; i < n-s.length(); i++) {
            System.out.print("0");
        }
        }
        // TODO code application logic here
    }
    
}