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.io.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.util.StringTokenizer;

public class Main {

	public static void main(String[] args) throws IOException {
		BufferedReader tec = new BufferedReader(new InputStreamReader(System.in)); 
		StringTokenizer linea = new StringTokenizer(tec.readLine());
		int n = Integer.parseInt(linea.nextToken());
		String m=linea.nextToken();
		String s ="";
		if(m.equals("10")) {
			if (n==1) {
				System.out.println("-1");
			}else {
				s="1";
				for (int i = 0; i < n-1; i++) {
					s+=0;
				}
				
			}
		}
		else {
		for (int i = 0; i < n; i++) {
		s+=m;
		}}
		System.out.println(s);
	}

}