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

public class Main {

	public static void main(String[] args) throws NumberFormatException, IOException {

		BufferedReader bf =  new BufferedReader(new InputStreamReader(System.in));
		//BufferedReader bf =  new BufferedReader(new FileReader("p.txt"));

		while (bf.ready()) {
			StringTokenizer tk = new StringTokenizer(bf.readLine());
			
			int n = Integer.parseInt(tk.nextToken());
			int t = Integer.parseInt(tk.nextToken());
			
			StringBuilder str = new StringBuilder();
			
			if (t == 10 && n == 1) {
				System.out.println("-1");
			}else {
				
				str.append(t);
				
				for (int i = 0; i < n-1; i++) {
					str.append("0");
				}
				
				if (t == 10) {
					str.deleteCharAt(str.length()-1);
				}
				
			}
			
			System.out.println(str);
			
		}
	}
}