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 JavaApplication420 {
// Olesya and Rodion
    public static void main(String[] args) {
       Scanner input=new Scanner(System.in);
       int n=input.nextInt();
       int t=input.nextInt();
       if(n==1 && t==10)
                 System.out.println(-1);
                 else{
                         System.out.print(t);
                         if(t==10)
                           for(int i=0;i<n-2;i++)
                               System.out.print(0);
else
       for(int i=0;i<n-1;i++)
                               System.out.print(0);                      
                         }
      {
              
              }
               
    }
    
}