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 a584 {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner sc=new Scanner(System.in);
		int n=sc.nextInt();
		int t=sc.nextInt();
		String s=Integer.toString(t);
		if(n==1 && t==10)
			System.out.println("-1");
		else if(s.length()==n)
			System.out.println(s);
		else{
			for(int i=0;i<n-1;i++)
				s+="0";
			if(t==10)
				s=s.substring(0,n);
			System.out.println(s);
		}
		sc.close();
	}

}