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.*;
public class ProA {
	static StreamTokenizer in=new StreamTokenizer(new BufferedReader(new InputStreamReader(System.in)));
	static int nextInt() throws IOException    
	{  
	    in.nextToken();    
	    return (int)in.nval;     
	}
	static String next() throws IOException    
	{  
	    in.nextToken();    
	    return in.sval;     
	}
	static PrintWriter out=new PrintWriter(new OutputStreamWriter(System.out));
	static int n,t;
	static String ans="";

	public static void main(String[] args) throws IOException {
		n=nextInt();t=nextInt();
		if(t==10&&n==1) ans="-1";
		else if(t==10)
		{
			ans="1";
			for(int i=1;i<n;i++)
				ans+='0';
		}
		else
		{
			for(int i=0;i<n;i++)
				ans+=(char)('0'+t);
		}
		System.out.println(ans);
	}
}