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.*;


import java.lang.*;
import java.math.BigInteger;
import java.io.*;
public class Main{
	public static void main (String[] args) throws java.lang.Exception{
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int t = scan.nextInt();
		String num = Integer.toString(t);
		int i = 1;
		if(t == 10)
			i++;
		for( ; i < n; i++)
			num += "0";
		if(t == 10 && n == 1)
			System.out.println(-1);
		else
			System.out.println(num);	
		scan.close();
	}
}