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.*;
import java.util.*;

public class Main {

    public static void main(String[] args ) {
        Scanner sc = new Scanner(System.in);
        int n= sc.nextInt();
        int t= sc.nextInt();
        //System.out.println(n);
        //System.out.println(t);
        if (t<10)
        {
            for(int i=0;i<n;i++)
            {
                System.out.print(t);
            }
            System.out.println();
        }
        else
        {
            if(n<2)
                System.out.println("-1");
            else{for(int i=0;i<n-1;i++)
            {
                System.out.print("1");
            }
            System.out.print("0");}
        }
        //System.out.println(n);
    }

}