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.*;
public class mohammad
{
  public static void main (String[]args)
  {
    Scanner U = new Scanner (System.in);
    int n = U.nextInt();
    int t = U.nextInt();
    if(n==1&&t==10)
            System.out.println(-1);
    else if(t<10)
    for( int i=0 ; i<n ; i++)
        System.out.print(t);
    if(n%2!=0 && t==10 &&n>1)
        System.out.print(1);
    if(t==10)
            for( int j=0 ; j<n/2 ; j++)
            System.out.print(t);
    
    }
}