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 MyClass {
    public static void main(String args[]) {
     Scanner sc=new Scanner(System.in);
     int n=sc.nextInt();
     int t=sc.nextInt();
    if(t==10)
    {
        if(n==1)
        {
            System.out.println(-1);

        }
        else{

            for(int i=0;i<n-1;i++)
            {
                System.out.print(1);
            }
            System.out.println(0);
        }
    }
    else{
        for(int i=0;i<n;i++)
        {
            System.out.print(t);
        }
        
    } 
}
}