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:
/**
 * Created by 11096 on 2017/9/21.
 */
import java.util.Scanner;
import java.math.BigInteger;

public class Main {


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

        BigInteger t=in.nextBigInteger();
        if(n==1&&t.compareTo(BigInteger.valueOf(10))==0)
        {
            System.out.println("-1");
        }
        else
        {
            n--;
            BigInteger ans=BigInteger.ONE;
            while(n-->0)
            {
                ans=ans.multiply(BigInteger.TEN);
            }
            System.out.println(ans.divide(gcd(ans,t)).multiply(t));
        }
    }
    public static BigInteger gcd(BigInteger a,BigInteger b)
    {
        if(a.compareTo(BigInteger.ZERO)==0)return b;
        else return gcd(b.mod(a),a);
    }
}