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.Scanner;


public class OlesyaRodion {

	public static void main(String[] args) {
		// TODO Auto-generated method stub
		Scanner vk = new Scanner(System.in);
        int n = vk.nextInt();
        int t = vk.nextInt();
        String s = ""+t;
        while(s.length()<n){
        	s += '0';
        }
        if(s.length()>n){
        	System.out.println(-1);
        }
        else{
        	System.out.println(s);
        }
        vk.close();
	}

}