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.util.*;
import java.io.*;

public class Main {
    static Scanner sc = new Scanner(System.in);

    static void run() {
        int n=sc.nextInt();
        int t=sc.nextInt();
        StringBuilder sl=new StringBuilder();
        sl.append(Integer.valueOf(t));
        int sx=sl.length();
        for(int i=0;i<n-sx;++i)sl.append("0");
        if(n==1 && t==10) System.out.println("-1");
        else System.out.println(sl);
    }

    public static void main(String[] args) {
        run();
    }
}