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 OlesyaandRodion {
	static int K, T;
	static Scanner scan;

	public static void main(String[] args) {
		scan = new Scanner(System.in);
		K = scan.nextInt();
		T = scan.nextInt();
		if (T == 10 && K == 1) {
			System.out.print(-1);
			System.exit(0);
		}
		if (T == 10) {
			System.out.print(1);
			for (int i = 0; i < K - 1; i++) {
				System.out.print(0);
			}
			System.exit(0);

		}
		for (int i = 0; i < K; i++) {
			System.out.print(T);
		}
	}
}