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 Vung {
	
	public static void main(String[] args) {
		
		Scanner scan = new Scanner (System.in);
		
		int a=scan.nextInt();
		int b=scan.nextInt();
		int digit=a;
		if (b==10) digit = a-1;
		
		if (digit==0){
			System.out.println("-1");
			return;
		}
		
		System.out.printf("%d", b);
		for (int i = 0; i<digit-1; i++){
			System.out.printf("0");
		}

	}

}