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 Main
{
	public static void main(String[] args) {
		Scanner scanner = new Scanner(System.in);
		
		int n = scanner.nextInt();
		int t = scanner.nextInt();
		
		if(n == 1 && t == 10) System.out.print(-1);
		else{
		    System.out.print(t);
		    if(t == 10){
		        for(int i = 0; i < n-2 ; i++)
		            System.out.print(0);
		    } else{
		        for(int i = 0; i < n-1 ; i++)
		            System.out.print(0);
		    }
		}
	}
}