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.math.BigInteger;
import java.util.Scanner;

public class One {

	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		int t = sc.nextInt();

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

		BigInteger b = BigInteger.valueOf(10L);
		b = b.pow(n);
		b = b.divide(BigInteger.valueOf(t));
		b = b.multiply(BigInteger.valueOf(t));
		b = b.subtract(BigInteger.valueOf(t));

		System.out.println(b);
	}

}