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.StringTokenizer;


public class PR {

   
    public static void main(String[] args) throws IOException{
      BufferedReader read=new BufferedReader(new InputStreamReader(System.in));
      StringTokenizer st=new StringTokenizer(read.readLine());
      int n= Integer.parseInt(st.nextToken());
      int t= Integer.parseInt(st.nextToken());
       
      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);
         }
    
    }              
                  
    }