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.Arrays;
import java.util.Scanner;


public class CF324A {

	public static void main(String[] args) {
		Scanner scan = new Scanner(System.in);
		int n = scan.nextInt();
		int t = scan.nextInt();
		if(t !=10){
			String result = String.valueOf(t);
			char c = '0';
			char[] repeat = new char[n-1];
			Arrays.fill(repeat, c);
			result += new String(repeat);
			System.out.println(result);
		}
		else{
			if(n==1){
				System.out.println(-1);
			}
			else{
				String result = String.valueOf(t);
				char c = '0';
				char[] repeat = new char[n-2];
				Arrays.fill(repeat, c);
				result += new String(repeat);
				System.out.println(result);
			}
		}

	}

}