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 codeforcesA {

	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int n = in.nextInt();
		int k = in.nextInt();
		StringBuilder sb = new StringBuilder();
		if (n==1&&k==10){
			System.out.println(-1);
		} else {
			sb = new StringBuilder();
			if (k<=9){
				for (int i = 0; i<n; i++){
					sb.append((char)(k+48));
				}
			} else {
				sb.append('1');
				for (int i = 1; i<n; i++) sb.append('0');
			}
		}
		System.out.println(sb);
	}

}