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.math.BigInteger;
import java.util.Scanner;
public class Tester {
	private static Scanner input;

	public static BigInteger powB(int x,int n)
	{
		BigInteger z = BigInteger.valueOf(1);
		while(n > 0)
		{
			z = z.multiply(BigInteger.valueOf(x));
			n--;
		}
		return z;
	}

	public static void main(String[] args) {
		BigInteger x = BigInteger.valueOf(1);
		input = new Scanner(System.in);
		int n,t,ans = 0;
		n = input.nextInt();
		t = input.nextInt();
		x = powB(10,n-1);
		BigInteger z = x.multiply(BigInteger.valueOf(10));
		for(;x.compareTo(z) == -1;x = x.add(BigInteger.valueOf(1)))
		{
			if((x.mod(BigInteger.valueOf(t))) == BigInteger.valueOf(0))
			{
				System.out.print(x);
				return ;
			}
		}
		System.out.print("-1");
	}

}