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 apples {
	public static void main(String args[])
	{
		Scanner user = new Scanner(System.in);
	    int n = user.nextInt();
	    int t = user.nextInt();
	    BigInteger x = new BigInteger("10");
	    if(n == 1 && t == 10)
	    {
	    	System.out.println(-1);
	    }
	    else if(t == 10)
	    {
	    	BigInteger y = x.pow(n - 1);
	    	System.out.println(y);
	    }
	    else
	    {
	    	BigInteger z = x.pow(n - 1).multiply(BigInteger.valueOf(t));
	    	System.out.println(z);
	    }
	}
}