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.FileNotFoundException;
import java.io.FileReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.Collections;
import java.util.HashMap;
import java.util.HashSet;
import java.util.Map.Entry;
import java.util.Scanner;
import java.util.Set;
import java.util.StringTokenizer;
import java.util.TreeMap;
import java.util.Vector;


public class hazem {
	static long A,B,m,t,l;

	public static void main(String[] args) throws IOException{
		
		FastScanner sc = new FastScanner();
	    PrintWriter out = new PrintWriter(System.out);
	    String n =sc.nextToken();
	    String t= sc.nextToken();
	    if(n.equals("1")& t.equals("10")){
	    	System.out.println(-1);
	    	return;
	    }
	    int nn =Integer.parseInt(n);
	    int tt =Integer.parseInt(t);
	    if(nn<t.length()){
	    	System.out.println(-1);
	    	return;
	    }
	    int zero= nn-t.length();
	    String ans= t ;
	    for(int i=0;i<zero;i++)
	    	ans+="0";
	    System.out.println(ans);
	   
	   
	  
	  
	    	
	    	
	    	
	    	
	    	
	    	
	    	
	    	
	    }
	
	

	    
	    
	    


	


	
	

	
	
}


	    	
	
 	


	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
	    
  

	  
	   
	    	
	    	
	 
	    
	    
	    		
	  	
	    	
	    	
	 
	 















class FastScanner {




    BufferedReader br;
    StringTokenizer st;

    public FastScanner() {
        br = new BufferedReader(new InputStreamReader(System.in));
    }

    public FastScanner(String s) {
        try {
            br = new BufferedReader(new FileReader(s));
        } catch (FileNotFoundException e) {
            e.printStackTrace();
        }
    }

    String nextToken() {
        while (st == null || !st.hasMoreElements()) {
            try {
            	
                st = new StringTokenizer(br.readLine());
            } catch (IOException e) {
                e.printStackTrace();
            }
        }
        return st.nextToken();
    }

    int nextInt() {
        return Integer.parseInt(nextToken());
    }

    long nextLong() {
        return Long.parseLong(nextToken());
    }

    double nextDouble() {
        return Double.parseDouble(nextToken());
    }
 
  
}