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.io.*;
import java.math.*;

public class Main
{
	public static void main (String[] args)
	{
		Scanner cin = new Scanner(System.in);
		int n = cin.nextInt();
		BigInteger t = cin.nextBigInteger();
		BigInteger a = BigInteger.valueOf(10).pow(n - 1);
		while (a.mod(t).compareTo(BigInteger.ZERO) != 0)
			a = a.add(BigInteger.ONE);
		if (a.compareTo(BigInteger.valueOf(10).pow(n)) >= 0)
			System.out.println("-1");
		else
			System.out.println(a);
	}
}