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.Closeable;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;

public class Task584A {

    public static void main(String[] args) {
        Reader in = new Reader();
        PrintWriter out = new PrintWriter(System.out);
        solve(in, out);
        in.close();
        out.close();
    }

    private static void solve(final Reader in, final PrintWriter out) {
        int n = in.nextInt();
        int t = in.nextInt();

        if (t == 10 && n == 1) {
            out.println(-1);
            return;
        }
        out.println(t + "0".repeat(Math.max(0, n - 1 - t / 10)));
    }

    private static class Reader implements Closeable {
        private BufferedReader bufferedReader;
        private StringTokenizer tokenizer;

        Reader() {
            bufferedReader = new BufferedReader(new InputStreamReader(System.in), 8192);
        }

        String next() {
            return getTokenizer().nextToken();
        }

        int nextInt() {
            return Integer.parseInt(next());
        }

        long nextLong() {
            return Long.parseLong(next());
        }

        private StringTokenizer getTokenizer() {
            while (tokenizer == null || !tokenizer.hasMoreTokens()) {
                try {
                    tokenizer = new StringTokenizer(bufferedReader.readLine());
                } catch (IOException e) {
                    throw new RuntimeException(e);
                }
            }
            return tokenizer;
        }

        @Override
        public void close() {
            tokenizer = null;
            try {
                bufferedReader.close();
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
    }
}