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.File;
import java.io.FileNotFoundException;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.Scanner;

public class Main {

    public static void main(String[] args) {
        Scanner in = new Scanner(System.in);
        int n, i;
        String S="1", t;
        n = in.nextInt();
        t = in.next();
        if (t.equals("10") && n==1) {
            System.out.println(-1);
            return;
        }
        while (S.length() < n) S+='0';
        BigInteger X = new BigInteger(S), T = new BigInteger(t), Z = new BigInteger("0"), E = new BigInteger("1");
        for (i=0; i<20; i++)
        {
            if (X.mod(T).compareTo(Z) == 0)
            {
                System.out.println(X);
                return;
            }
            X = X.add(E);
        }
    }
}