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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.math.BigInteger;

public class Main {
    public static void main(String[] args) {
        BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

        try {
            String []line = br.readLine().split("\\s+");
            int n = Integer.parseInt(line[0]);
            int t = Integer.parseInt(line[1]);

            BigInteger number = BigInteger.valueOf(10).pow(n - 1);
            BigInteger check = number.multiply(BigInteger.valueOf(10));

            if (number.compareTo(BigInteger.valueOf(t)) < 0) {
                number = BigInteger.valueOf(t);
            }
            else if (number.compareTo(BigInteger.valueOf(t)) > 0) {
                BigInteger temp = number.add(BigInteger.valueOf(t - 1)).divide(BigInteger.valueOf(t));
                number = temp.multiply(BigInteger.valueOf(t));
            }

            if (number.compareTo(check) >= 0) {
                System.out.println("-1");
            }
            else {
                System.out.println(number);
            }


        } catch (IOException e) {
            e.printStackTrace();
        }

    }
}