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.lang.*;
import java.util.*;

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