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.HashMap;
import java.util.Scanner;

public class OlesyaAndRodian
{

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

}