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.Scanner;

public class ProblemA324DIV2 {
	
	
	public static void main(String[] args)	{
		Scanner in = new Scanner(System.in);
		int n, t, nodn, nodt;
		String s="";
		n = in.nextInt();
		t = in.nextInt();
		
		nodn = (int) Math.floor(Math.log10(n) + 1);
		nodt = (int) Math.floor(Math.log10(t) + 1);
		
		if(t==10 && n==1)	{
			System.out.println(-1);
			in.close();
			return ;
		}
		
		s = "" + t;
		for(int i=0; i<n - nodt; i++)	{
			s += "0";
		}
		System.out.println(s);
		in.close();
	}
}