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 MyClass {
    

     public static void main(String[] args) {
     Scanner scan = new Scanner(System.in);
     int n = scan.nextInt();
     int t = scan.nextInt();

    if(n == 1 && t == 10)
    {
        System.out.println(-1);
    }
    else
    {
        if(t == 10)
            t = 1;
        String result = "" + t;
        for(int i = 0; i<n-1; i++)
        {
            result = result + "0";
        }
  
        System.out.println(result);
    } 
  }
    
}