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:

/**
 *
 * @author Gourav
 */
//import java.util.*;
 import java.math.BigInteger;
import java.util.Scanner;
//import java.math.*;
public class Program {

       
    public static void main(String args[]){		
    Scanner sc=new Scanner(System.in);
	 int n=sc.nextInt();
	 int t=sc.nextInt();
	 if((""+t).length()>n){
             
		 System.out.println("-1");
	 }else{
		 String s=""+t;
		 for (int i =(""+t).length(); i <n; i++) {
			s=s+"0";
                      //  System.out.println(s);
		}
		 System.out.println(s);
	 }
}
}