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.*;
public class test {
	public static void main(String[] args) {
		
		Scanner keyboard = new Scanner(System.in);
		int LengthOfDigit = keyboard.nextInt();
		int DivisibleBy = keyboard.nextInt();
		if(LengthOfDigit==1 && DivisibleBy == 10) {
			System.out.println("-1");
			return;
		}
		String answer = Integer.toString(DivisibleBy);
		
		LengthOfDigit--;
		if(DivisibleBy==10) {
			LengthOfDigit--;
		}
		while(LengthOfDigit!=0) {
			answer = answer + "0";
			LengthOfDigit--;
		}
		System.out.println(answer);
	 }
}