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.Scanner;

public class Problem584A {

    public static void main(String[] args) {
        String input = input();
        Pair<Integer, Integer> pair = parse(input);

        Integer lengthOfNumber = pair.getFirst();
        Integer divider = pair.getSecond();

        BigInteger from =  BigInteger.TEN.pow(lengthOfNumber - 1);
        BigInteger till =  BigInteger.TEN.pow(lengthOfNumber).subtract(BigInteger.ONE);

        BigInteger result = BigInteger.ZERO.subtract(BigInteger.ONE);
        if (BigInteger.valueOf((long) divider).compareTo(till) < 1) {
            BigInteger current = from;
            while (current.remainder(BigInteger.valueOf((long) divider)).compareTo(BigInteger.ZERO) != 0) {
                current = current.add(BigInteger.ONE);
            }
            result = current;
        }

        System.out.println(result);
    }

    private static Pair<Integer, Integer> parse(String string) {
        String[] strPair = string.split(" ");
        return new Pair<>(Integer.valueOf(strPair[0]), Integer.valueOf(strPair[1]));
    }

    private static String input() {
        Scanner scanner = new Scanner(System.in);
        scanner.useDelimiter(System.lineSeparator());
        String input = scanner.next();
        scanner.close();
        return input;
    }

    private static class Pair<T, V> {
        private T first;
        private V second;

        Pair(T first, V second) {
            this.first = first;
            this.second = second;
        }

        T getFirst() {
            return first;
        }

        V getSecond() {
            return second;
        }
    }

}