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