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.io.BufferedReader;
import java.io.InputStreamReader;
import java.io.PrintWriter;

public class Main {

	public static void main(String[] args) throws Exception {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		PrintWriter pw = new PrintWriter(System.out);
		String[] l = br.readLine().split(" ");
		int n = Integer.parseInt(l[0]);
		int t = Integer.parseInt(l[1]);
		
		String res = "";
		if(t<10)
			for(int i=0;i<n;i++)
				res+=t;
		else if(n==1)
			res+=-1;
		else{
			for(int i=0;i<n-1;i++)
				res+=1;
			res+=0;
		}
		pw.println(res);
		
		pw.flush();
		pw.close();
		br.close();
	}
}