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.io.File;
import java.io.FileNotFoundException;
import java.math.BigInteger;
import java.util.Scanner;

public class Temp {
	public static void main(String [] args) throws FileNotFoundException {
		Scanner in = new Scanner(System.in);
		int n = in.nextInt();
		int t = in.nextInt();
		String s = "";
		if(t<10) 
			for(int i = 0; i < n; i++)
				s+=t;
		else {
			if(n==1) s="-1";
			else{
				for(int i = 0; i < n-1; i++)
					s+="1";
				s+="0";
			}
		}
		System.out.println(s);
		in.close();
	}
}