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.DataInputStream;
import java.io.IOException;
import java.util.Scanner;

public class Main {

    static int n;
    static int t;
    static int p = 1;

    static String zeros = "0000000000";
    static String zz[] = {
            "", "0", "00", "000", "0000",
            "00000", "000000","0000000","00000000","000000000",
            "0000000000","00000000000", "000000000000", "0000000000000", "00000000000000",
            "000000000000000","0000000000000000","00000000000000000","000000000000000000","0000000000000000000","00000000000000000000"};

    static private void printError() {
        System.out.println(-1);
    }

    static private void printAnswer(int number, int n) {
        System.out.print(number);
        int longs = n / 10;
        int mod = n % 10;
        for (int i = longs; i > 0; i--) {
            System.out.print(zeros);
        }
        if (mod != 0) {
            System.out.print(zz[mod]);
        }
        //System.out.println();
    }

    public static void main(String[] args) {
        Scanner input = new Scanner(System.in);

        if (input.hasNextInt()) {
            n = input.nextInt();
        } else {
            printError();
            return;
        }
        if (input.hasNextInt()) {
            t = input.nextInt();
        } else {
            printError();
            return;
        }

        if (n < 1 || n > 100 || t < 2 || t > 10) {
            printError();
            return;
        }

        if (t < 10) {
            printAnswer(t, n - 1);
        } else if (t == 10) {
            if (n == 1)
                printError();
            else
                printAnswer(t, n - 2);
        } else {
            printError();
            return;
        }
    }
}