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 JavaApplication1 {

    static Scanner input = new Scanner(System.in);
    public static void main(String[] args) throws InterruptedException {
        
        int n=input.nextInt() , t=input.nextInt();
        
        if( n==1 && t==10)
            System.out.println("-1");
        else if( t==10){
             for( int i=0 ; i<n-1 ; i++ )
                 System.out.print(1);
             
             System.out.print("0");
        }
        else {
            for( int i=0 ; i<n ; i++ )
               System.out.print(t);
        }
        
    }
    
}