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.Arrays;
import java.util.Scanner;
import java.util.StringTokenizer;

public class Main {


    public static void main(String[] args) throws FileNotFoundException {
        //InputStream inputStream = new FileInputStream("input.xml");
        InputStream inputStream = System.in;
        OutputStream outputStream = System.out;
        InputReader in = new InputReader(inputStream);
        PrintWriter out = new PrintWriter(outputStream);
        Task task = new Task();
        task.solve(in, out);
        out.close();

    }

    static class Task {
        public void solve(InputReader in, PrintWriter out) {
           long n = in.nextInt(); // считывает целое число с потока ввода и сохраняем в переменную
            int t= in.nextInt();
           char[] p=new char[105];

           if(t<10) {
               for (int i = 0; i < n; i++)
                   out.printf("%c",0x30+t);

           }
            else if(t==10){
               if(n==1)
                   out.printf("%d",-1);
               else{
                   for (int i = 0; i < n-1; i++)
                       out.printf("%c",0x31);
                       out.printf("%d",0);
               }

           }
        }
    }

    static class InputReader {
        public BufferedReader reader;
        public StringTokenizer tokenizer;

        public InputReader(InputStream stream) {
            reader = new BufferedReader(new InputStreamReader(stream), 32768);
            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());
        }

    }


}