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 round324;

import java.util.Scanner;

public class OlesyaAndRodion {

	public static void main(String[] args) {

		Scanner s = new Scanner(System.in);

		int n = s.nextInt();
		int t = s.nextInt();

		if (n == 1) {
			if (t == 10)
				System.out.println(-1);
			else
				System.out.println(t);
		}

		else {
			if (n == 2) {
				if (t == 10)
					System.out.println(t);
				else
					System.out.println(11 * t);
			} else {
				if (t == 10) {
					System.out.print(1);
					for (int i = 1; i < n; i++) {
						System.out.print(0);
					}
				} else {
					System.out.print(t);
					for (int i = 2; i < n; i++)
						System.out.print(0);
					System.out.println(t);
				}
			}
		}

	}

}