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.math.BigInteger;
import java.util.*;
import java.util.regex.Matcher;

public class Codeforces {

    public static void main(String[] args) {
        Scanner s = new Scanner(System.in);

        int n = s.nextInt();
        int k = s.nextInt();

        if (k == 10 ) {
            if (n == 1) {
                System.out.print(-1);
            } else {
                System.out.print(1);
                for (int i = 1; i < n; i++) {
                    System.out.print(0);
                }
            }
        } else {
            for (int i = 0; i < n; i++) {
                System.out.print(k);
            }
        }
    }
}