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 A324 {

	public static void main(String[] args) {
		Scanner in = new Scanner(System.in);
		int n=in.nextInt();
		int t=in.nextInt();
		if(n==1&&t==10)
			System.out.println("-1");
		else{
		String ans=t+"";
		int s=1;
		if(t==10)
			s=2;
		for( int i=s;i<n;i++){
			ans+="0";
		}
		System.out.println(ans);
		}
	}

}