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:
//package olysea;

import java.util.Scanner;

public class Olysea {

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

}