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 Problem584A {
    public static void main (String[] args) {
        Scanner sc = new Scanner (System.in);
        int n = sc.nextInt();
        int difference = n-19;
        long t = sc.nextInt();
        long start = 0, result = 0;
        if (Math.pow(10, n) <= t) {
            result = -1;
            System.out.println(result);
        }
        else {
            if (n>19) {
                start = (long) Math.pow(10, 18);
                long spare = start%t;
                long resultL = start+(t-spare);
                String resultS = ""+resultL;
                for (int i = 0; i < difference; i++) {
                    resultS+="0";
                }
                System.out.print(resultS);
            }
            else {
                start = (long) Math.pow(10, n-1);
                long spare = start%t;
                result = start+(t-spare);
                System.out.println(result);
            }
        }
    }
}