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.Locale;
import java.util.Scanner;
import java.util.ArrayList;
import java.util.Collections;
import java.lang.String;
public class max {
    public static void main(String []args){
        Scanner sc = new Scanner(System.in);
      int n = sc.nextInt();
      int m = sc.nextInt();
      int number =m;
      int count = 0;
      while(number>0)
      {
          number = number/10;
          count++;
      }
      if(count>n)
       System.out.println("-1");
      else if(count==n)
          System.out.println(m);
      else
      {
          count = n-count;
          System.out.print(m);
          while(count>0)
          {
              System.out.print("0");
              count--;
          }

      }
    }
}