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

import static java.lang.Integer.parseInt;

public class Main {

    public static void main(String[] args)throws IOException {
        BufferedReader in = new BufferedReader(new InputStreamReader(System.in));
        StringTokenizer st = new StringTokenizer(in.readLine());
        String n1 = st.nextToken();
        String t1 = st.nextToken();

        int n = parseInt(n1);
        int t = parseInt(t1);
        if (t1.length() > n)
        {
            System.out.println(-1);
        }
        else
        {
            String out = "";
            if (t == 10)
            {
                out += 1;
                n--;
                for (int i = 0; i < n; i++) {
                    out +=0;
                }
            }
            else
            {

                for (int i = 0; i < n; i++)
                {
                    out += t;
                }
            }

            System.out.println(out);
        }
    }
}