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.*;


public class cp{
	public static void main(String[] args) {
		
		Scanner sc = new Scanner(System.in);

		int len = sc.nextInt();
		int div = sc.nextInt();

		if(div==10)
		{
			if(len==1)
			{
				System.out.println("-1");
			}else
			{
				System.out.print("1");
				for(int i=0;i<len-1;i++)
				{
					System.out.print("0");
				}System.out.println("");
			}

		}else{

			for(int i=0;i<len;i++)
			{
				System.out.print(div);
			}
			System.out.println("");

		}
	}
}