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.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
public class Codechef
{
	public static void main (String[] args) throws java.lang.Exception
	{    //String s="";
	     //long ans=-1;
	     int n=0;
	     //boolean b=true;
	     String s=null;
	     Scanner SC=new Scanner(System.in);
	     BufferedReader br=new BufferedReader(new InputStreamReader(System.in));
		if(SC.hasNext())
		n=SC.nextInt();
		//long arr[]=new long[n];
	     //Vector<Integer> vec=new Vector();
	     int t=0;
	     if(SC.hasNext())
	     t=SC.nextInt();
	     
	     if(n==1&&t==10)
	     s=(Integer.toString(-1));
	     
	     else if(t!=10)
	     {    s=Integer.toString(t);
	          for(int i=0;i<n-1;i++)
	          {
	               s=s+Integer.toString(t);
	          }
	          
	     }
	     
	     else
	     {
	          s=Integer.toString(1);
	          for(int i=0;i<n-1;i++)
	          {
	               s=s+(Integer.toString(0));
	          }
	     }
	     System.out.println(s);
	}
}