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.Scanner;
public class HelloWorld{

     public static void main(String []args){
        //System.out.println("Hello World");
        String s1=new String();
        int i,n,t,res=0,size,p=0;
       
        Scanner sc=new Scanner(System.in);
        n=sc.nextInt();
        t=sc.nextInt();
        char ch;
        
        
            if((n==1)&&(t==10))
            {
               p++;
               System.out.print("-1");
            }
            else
            {
                if(n==1)
                {
                    res=t*1;
                
                }
                if(n==2)
                {
                    res=t*6;
                }
                if(n>2)
                {
                    if((t==3)||(t==9))
                    {
                        res=t*2;
                        res=res-1;
                        s1=String.valueOf(res);
                        size=s1.length();
                        size=n-size;
                        for(i=0;i<size;i++)
                        {
                            if(i==0)
                                ch='1';
                            else
                            {
                                ch='0';
                            }
                            System.out.print(ch);
                        }
                    }
                
                //res=t*2;
                    if(t==6)
                    {
                        res=t*1;
                        //res=res-1;
                        s1=String.valueOf(res);
                        for(i=0;i<n-1;i++)
                        {
                        
                            ch='6';
                            System.out.print(ch);
                        } 
                    }
                
                
                    if(t==7)
                    {
                        res=t*1;
                        //res=res-1;
                        s1=String.valueOf(res);
                        for(i=0;i<n-1;i++)
                        {
                        
                            ch='7';
                            System.out.print(ch);
                        } 
                    }
                    if((t==2)||(t==4)||(t==5)||(t==10))
                    {
                        res=t*2;
                        //res=res-1;
                        s1=String.valueOf(res);
                        size=s1.length();
                        size=n-size;
                        for(i=0;i<size;i++)
                        {
                            if(i==0)
                                ch='1';
                            else
                            {
                                ch='0';
                            }
                            System.out.print(ch);
                        }
                        
                    }
                    
                    
                    if(t==8)
                    {
                        res=t*1;
                        //res=res-1;
                        s1=String.valueOf(res);
                        for(i=0;i<n-1;i++)
                        {
                        
                            ch='8';
                            System.out.print(ch);
                        } 
                    }
                
                }
                
                if(n>2)
                {
                    System.out.println(s1);
                }
                else
                {
                    System.out.println(res);
                }
            
            }
        
            
        
     }
}