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.util.Scanner;
public class CF0584A
{
 static Scanner sIn = new Scanner(System.in);
 public static void main(String[] learnRussian)
 {
  int n = sIn.nextInt();
  int t = sIn.nextInt();
  StringBuilder sB = new StringBuilder();
  if (t == 10)
  {
   if (n == 1)
    sB.append("-1");
    else
    {
     for (int i = 1; i < n; i ++)
      sB.append('1');
     sB.append('0');
    }
  }
   else
    for (int i = 0; i < n; i ++)
     sB.append(t);
  System.out.println(sB);
 }
}