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.math.BigInteger;
import java.util.*;

public class codeforces {

    public static void main(String[] args) {

        Scanner input = new Scanner(System.in);


        long n = input.nextInt();
        long t = input.nextInt();

        if(n==1&&t==10)
            System.out.println(-1);
        else
        {
            String r = "";
            r+=Long.toString(t==10?1:t);
            n--;
            while(n-->0)
                r+="0";

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