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 Main{


public static void main(String args[])
{
Scanner in = new Scanner(System.in);

int n =in.nextInt();
int t =in.nextInt();

String s ="";

if(n==1&&t==10)
{
System.out.println(-1);
return;
}

if(t!=10)
{
for(int i=0 ; i<n ;i++)
s+=t+"";
}

else
{ s="1";
for(int i=1 ;i<n;i++)
s+="0";
}

System.out.println(s);
}

}