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 code_forces;
import java.math.BigInteger;
import java.util.*;
public class Problem_584A
{
	public static void main(String[] args)
	{
		Scanner sc= new Scanner(System.in);
		int n=sc.nextInt();
		int t=sc.nextInt();
		String s=""+t;
		if(t!=10)		
			while(s.length()<n)
				s+=""+t;
		else
			while(s.length()<n)
				s+=""+0;
		if(n<s.length())
			System.out.println(-1);
		else
			System.out.println(s);
	}
}