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 OlRadikNew {
	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int t = scan.nextInt();
		int outR = -1;
		if (n == 1&& t<10) {
			System.out.println(t);
		} else {
			if (t == 2) {
				System.out.print(1);
				for (int i = 0; i < n - 1; i++) {
					System.out.print(0);
				}
			}
			if (t == 3) {
				System.out.print(1);
				for (int i = 0; i < n - 2; i++) {
					System.out.print(0);
				}
				System.out.print(2);
			}
			if (t == 4) {
				if (n == 2) {
					System.out.println(12);
				} else {
					System.out.print(1);
					for (int i = 0; i < n - 1; i++) {
						System.out.print(0);
					}
				}
			}
			if (t == 5) {
				System.out.print(1);
				for (int i = 0; i < n - 1; i++) {
					System.out.print(0);
				}
			}
			if (t == 6) {
				System.out.print(6);
				for (int i = 0; i < n - 1; i++) {
					System.out.print(0);
				}
			}
			if (t == 7) {
				System.out.print(7);
				for (int i = 0; i < n - 1; i++) {
					System.out.print(0);
				}
			}
			if (t == 8) {
				System.out.print(8);
				for (int i = 0; i < n - 1; i++) {
					System.out.print(0);
				}
			}
			if (t == 9) {
				System.out.print(9);
				for (int i = 0; i < n - 1; i++) {
					System.out.print(0);
				}
			}
			if (t == 10) {
				if (n == 1) {
					System.out.println(-1);
				} else {
					System.out.print(1);
					for (int i = 0; i < n - 1; i++) {
						System.out.print(0);
					}
				}
			}
		}
	}
}