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.*;

public class Olesya_and_Rodion_Lvl1 {

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);

        BigInteger base = BigInteger.valueOf(10);
        int playerOne = in.nextInt();
        int playerTwo = in.nextInt();

        BigInteger rangeIs = (base.pow(playerOne).subtract(BigInteger.valueOf(1)));

        while (true) {
            if (rangeIs.compareTo(BigInteger.valueOf(0)) == 0) {
                System.out.println(-1);
                return;
            }
            if (rangeIs.mod(BigInteger.valueOf(playerTwo)).equals(BigInteger.valueOf(0))) {
                System.out.println(rangeIs);
                return;
            }
            rangeIs = rangeIs.subtract(BigInteger.valueOf(1));
        }
    }

}