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;
import java.io.PrintWriter;
import java.util.HashSet;
import java.util.Arrays;
import java.math.BigInteger;

public class A584 implements Runnable {
	private Scanner in = new Scanner(System.in);
	private PrintWriter out = new PrintWriter(System.out);
	private int l;
	private int d;
	private BigInteger ans = new BigInteger("-1");
	
	
	public static void main(String[] args) {
		new Thread(new A584()).start();
	}

	private void read() {
		l = in.nextInt();
		d = in.nextInt();
		
	}

	private void solve() {
		BigInteger ten = new BigInteger("10");
		BigInteger divider = new BigInteger(d+"");
		ten = ten.pow(l-1);
		
		for(BigInteger i = ten; i.compareTo(ten.multiply(BigInteger.TEN)) < 0; i = i.add(BigInteger.ONE)){
			if((i.divideAndRemainder(divider)[1]).compareTo(BigInteger.ZERO) == 0) {
				ans = i;
				break;
			}
		}

			
	}

	private void write() {
		
		out.println(ans);
		
	
	}

	public void run() {
		read();
		solve();
		write();
		out.close();
	}
}