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 Codeforces584A {
	public static void main(String args[])
	{
		
		Scanner s = new Scanner(System.in);
		int n = s.nextInt();
		long t = s.nextLong();
		s.close();
		long i=1;
		BigInteger min = BigInteger.valueOf(1);
		BigInteger result = BigInteger.valueOf(-1);
		while(i<n)
		{
			min=min.multiply(BigInteger.valueOf(10));
			i++;
		}
		BigInteger max = min.multiply(BigInteger.valueOf(10));
		while(min.compareTo(max)==-1)
		{
			if(min.mod(BigInteger.valueOf(t))==BigInteger.valueOf(0))
			{
				result = min;
				break;
			}
			min=min.add(BigInteger.valueOf(1));
		}
		System.out.println(result);
	}
}