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.OutputStream;
import java.io.IOException;
import java.io.InputStream;
import java.io.PrintWriter;
import java.util.Scanner;
import java.math.BigInteger;

/**
 * Built using CHelper plug-in
 * Actual solution is at the top
 */
public class Main
{
    public static void main(String[] args)
    {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        Scanner in = new Scanner(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(1, in, out);
        out.close();
    }

    static class TaskA
    {
        public void solve(int testNumber, Scanner in, PrintWriter out)
        {
            int n = in.nextInt();
            int t = in.nextInt();
            if (n == 1 && t == 10)
            {
                out.print(-1);
                return;
            } else if (n == 1)
            {
                out.print(t);
                return;
            }
            if (t == 10)
            {
                out.print(new BigInteger("10").pow(n - 1));
            } else
            {
                out.print((new BigInteger("10").pow(n - 1)).multiply(new BigInteger(String.valueOf(t))));
            }
        }

    }
}