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;
import java.lang.Math;

public class Problem1  {
	
	public static void main(String args[])  {
	
		Scanner keyboard = new Scanner(System.in);
		int n = keyboard.nextInt();
		int t = keyboard.nextInt();

		int r;	
		
			
		

		if (!((t==10)&&(n==1)))  {
			if (t!=10)  {
				for (int i = 1; i <= n; i++)  
					System.out.print(t);
				System.out.println();
			}  else  {
				for (int i = 1; i <= n-1; i++)  {
					System.out.print(8);
				}
				System.out.print(0);
				System.out.println();
			}
		}  else  {
			r = -1;
			System.out.println(r);
		}	
	}
}