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 _584A {
        public static void main(String[] args) {
            Scanner sc=new Scanner(System.in);
            int n=sc.nextInt();
            StringBuilder t= new StringBuilder(sc.next());
            String s="0";
            while(t.length()<n)
                t.append(s);
            System.out.println(t.length()==n?t:"-1");
            sc.close();
        }
}