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.Scanner;

/*
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/**
 *
 * @author Ivan
 */
public class firstProblem {

    /**
     * @param args the command line arguments
     */
    public static void main(String[] args) throws IOException {
        Scanner sc=new Scanner(System.in);
        int digits=sc.nextInt();
        int divisor=sc.nextInt();
        String number="";
        if(divisor==10&&digits==1)
        {
            System.out.println("-1");
            return;
        }
        number=Integer.toString(divisor);
        digits-=number.length();
        String filler="";
        while(digits!=0)
        {
            number+="0";
            digits--;
        }
        System.out.println(number);
    }
    
}