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.*;

public class Main
{
   public static void main(String[] arg)
   {
     Scanner sc= new Scanner(System.in);
     int i,j,k=-1,l1,l2,m,t,d1=0,d2,d3,a[]=new int[1000000],b[]=new int[1000000],min,max;
     String s;
     m=sc.nextInt();
     t=sc.nextInt();
    if(m==1 && t==10){
        System.out.println(-1);
    }else{
      System.out.print(t);
      
        if(t==10){
            m=m-1;
        }else if(m==1){
            m=0;
        }
        for(i=1;i<m;i++){
            System.out.print("0");
        }
    }
   
     System.out.println();
     
     
   }
 
 
}