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.*;
import java.math.BigInteger;

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

        while (sc.hasNextInt()) {
            int n = sc.nextInt();
            int t = sc.nextInt();

            String s = "1";

            while (s.length() != n) s += "0";

            BigInteger x = new BigInteger(s);
            BigInteger y = new BigInteger(s + "0");

            while (!x.equals(y)) {
                if (x.mod(new BigInteger("" + t)) == BigInteger.ZERO) {
                    break;
                }

                x = x.add(BigInteger.ONE);
            }

            if (x.equals(y)) {
                System.out.println(-1);
            } else {
                System.out.println(x);
            }
        }
    }
}