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;
import java.math.*;
public class A584 {
	public static void main(String[] args)
	{
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int t = scan.nextInt();
		if(n == 1 && t == 10)
		{
			System.out.println("-1");
		}
		else
		{
			String zer = new String("");
			int i=1;
			while(i<n)
			{
				zer+="0";
				i++;
			}
			BigInteger v = new BigInteger("1" + zer);
			BigInteger num = new BigInteger("" + t);
			while(v.mod(num).compareTo(BigInteger.ZERO) != 0)
			{
				v=v.add(BigInteger.ONE);
			}
			System.out.println(v);
		}
	}
}