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 OlseyaAndRodion {

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

	}

}