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.*;
import java.util.*;
import static java.lang.Math.*;
import java.math.BigInteger;

public class Test3 {

    public static void main(String[] args) {
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        TaskA solver = new TaskA();
        solver.solve(in, out);
        out.close();
    }
}

class TaskA {

    TaskA() {
    }

    public void solve(InputReader in, PrintWriter out) {

// ----------------- start --------------------
        int n = in.nextInt();
        int t = in.nextInt();
        boolean flag = false;
        
        BigInteger tt = BigInteger.valueOf(t);
        BigInteger s1 = new BigInteger("10");
        BigInteger first = s1.pow(n - 1);
        BigInteger last = s1.pow(n);
        BigInteger i = new BigInteger("1");
        //System.out.println(first.compareTo(last) < 0);
        for (; first.compareTo(last) < 0; first = first.add(BigInteger.ONE)) {
            if (first.mod(tt).compareTo(BigInteger.ZERO)==0) {
                flag = true;
                break;
            }
        }
        if (flag) {
            System.out.println(first);
        } else {
            System.out.println("-1");
        }

// ------------------- end ---------------------
    }
}

class InputReader {

    BufferedReader reader;
    StringTokenizer tokenizer;

    InputReader(InputStream stream) {
        reader = new BufferedReader(new InputStreamReader(stream));
        tokenizer = null;
    }

    public String next() {
        while (tokenizer == null || !tokenizer.hasMoreTokens()) {
            try {
                tokenizer = new StringTokenizer(reader.readLine());
            } catch (IOException e) {
                throw new RuntimeException(e);
            }
        }
        return tokenizer.nextToken();
    }

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

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

    double nextDouble() {
        return Double.parseDouble(next());
    }

    String nextLine() {
        String str = "";
        try {
            str = reader.readLine();
        } catch (IOException e) {
            e.printStackTrace();
        }
        return str;
    }
}