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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.Scanner;
import java.util.StringTokenizer;


public class Read {

    public static void main(String[] args)  {
       Scanner read=new Scanner(System.in);
      int n= read.nextInt();
      int t= read.nextInt();
       
      String ans = t+"";
         if(n==1 &t==10)
         {
             System.out.println(-1);
         }
         else{
        for (int i =1; i < n; i++) {
            if(t==10)
            ans=1+ans;
            else
                ans=t+ans;
        }
        if(t==10)
                 System.out.println(ans.substring(1));
        else
             System.out.println(ans);
         }
    }
    
}
class FastReader{
    BufferedReader br ;
    StringTokenizer st ;
    
    public FastReader(){
        br = new BufferedReader (new InputStreamReader(System.in));
        
    }
    
    
    String next(){
        while(st==null|| !st.hasMoreElements()){
            try{
                st=new StringTokenizer(br.readLine());
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            
        }
        return st.nextToken();
    }
    
    int nextInt(){
        
        return Integer.parseInt(next());
        
    }
    
    long nextLong(){
        return Long.parseLong(next());
    }
    
    double nextDouble(){
        return Double.parseDouble(next());
    
    }
    
    
    String nextLine(){
        String str ="";
        try{
            str=br.readLine();
        }
        catch(IOException e){
            e.printStackTrace();
        }
        return str;
    }
    
}