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.io.*;
import java.math.*;
 public class Main{
    static final long MOD = (long)1e9+7;
    static FastReader in;
    public static void main(String[] args){
        in = new FastReader();
        //process();
      run();
       // int t=ni();
      //  while(t-->0) run();
    }
    
    static void run(){
    int N=ni();
    int T=ni();
    StringBuilder ans=new StringBuilder();
    ans.append("1");
    for(int i=0;i<N-1;i++) ans.append("0");
    BigInteger big=new BigInteger(ans.toString());
    BigInteger remain=big.remainder( BigInteger.valueOf(T));
    int attach=T-remain.intValue();
    big=big.add(BigInteger.valueOf(attach));
    //big=big.add()
    if(N==1&&T==10) pn("-1");
    else pn(big);
    
    
    
          
          
          
          
           
                
                
                
        

    }
    
    static void p(Object o){
        System.out.print(o);
    }
    
    static void pn(Object o){
        System.out.println(o);
    }
    
    static String n(){
        return in.next();
    }
    
    static String nln(){
        return in.nextLine();
    }
    
    static int ni(){
        return Integer.parseInt(in.next());
    }
    
    static long nl(){
        return Long.parseLong(in.next());
    }
    
    static double nd(){
        return Double.parseDouble(in.next());
    }
    
    static 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();
        }
 
        String nextLine()
        {
            String str = "";
            try
            {
                str = br.readLine();
            }
            catch (IOException e)
            {
                e.printStackTrace();
            }
            return str;
        }
    }
}