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:

//package codeforces;
import java.math.BigInteger;
import java.util.ArrayList;
import java.util.Collections;
import java.util.HashSet;
import java.util.Scanner;
import java.util.Set;

public class HK {

    public static void main(String[] args) {

        Scanner in = new Scanner(System.in);

        //String p="abcdefghijklmnopqrstuvwxyz";
        Set<Integer> list = new HashSet<Integer>();
        Set<Integer> list2 = new HashSet<Integer>();

        ArrayList<Long> set = new ArrayList<Long>();
        int n = in.nextInt();
        int t = in.nextInt();
        if (n == 1 && t > 9) {
            System.out.println("-1");
        } else {

            BigInteger t1 = new BigInteger("" + 10);
            BigInteger t2 = new BigInteger("" + t);
            t1 = t1.pow(n - 1);
        
            t1 = t1.multiply(t2);
            if(t<10)
            {
               System.out.println("" + t1); 
            }
            else
            {
                t1=t1.divide(BigInteger.TEN);
                System.out.println(""+t1);
            }
            

        }

    }
}