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.HashMap;
import java.util.StringTokenizer;

public class Main {

    static int a[];
    static int l[];
    static int ans[];
    static HashMap<Integer, Boolean> map = new HashMap<>();

    public static void main (String [] args) throws Exception {
        InputReader reader = new InputReader();
        PrintWriter out = new PrintWriter(System.out);

        int n = reader.nextInt();
        int t = reader.nextInt();

        long ans=1;

        while(ans%t!=0){
            ans++;
        }

        long len=getLen(ans);

        StringBuilder str=new StringBuilder();
        String num=Long.toString(ans);
        str.append(num);

        if(n-len>=0){
            while(n-len>0){
                str.append("0");
                n--;
            }
            System.out.println(str);
        }else{
            System.out.println("-1");
        }
        out.flush();

    }

    static long getLen(long n){
        long c=0;
        while(n>0){
            c++;
            n=n/10;
        }
        return c;
    }

    static class InputReader {
        BufferedReader reader;
        StringTokenizer tokenizer;

        InputReader() {
            reader = new BufferedReader(new InputStreamReader(System.in));
            tokenizer = null;
        }

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

        int nextInt() {
            return Integer.parseInt(next());
        }
        double nextDouble() {
            return Double.parseDouble(next());
        }

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