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.*;
                    public class rodion{
                         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(); 
                            } 
                      
                            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; 
                            } 
                        } 
                        public static void main(String[] args)
                        {
                        FastReader sc=new FastReader();
                            int n=sc.nextInt();
                             int t=sc.nextInt();
                           
                             
                             
                             if(n==1&&t==10)
                              System.out.println(-1); 
                        else
                               {
                                   if(t==10)
                                   t=1;
                                   System.out.print(t);
                               for(int i=1;i<n;i++)
                               System.out.print(0);
                                
                            }
                            
                            
                            
                            
                        
                        
                        
                        
                    }
                    }