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.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.math.BigInteger;
import java.util.StringTokenizer;

public class _584A_OlesyaAndRodion {

	public static void main(String[] args) throws IOException {
		// TODO Auto-generated method stub
		BufferedReader br = new BufferedReader((new InputStreamReader(System.in)));
		PrintWriter pw = new PrintWriter(System.out);
		StringTokenizer st = new StringTokenizer(br.readLine());
		int n = Integer.parseInt(st.nextToken());
		int t = Integer.parseInt(st.nextToken());
		
		BigInteger i = new BigInteger(String.format("%.0f", Math.pow(10, n - 1)));
		BigInteger c = (new BigInteger(String.format("%.0f", Math.pow(10, n))));
		while (true) {
			if (i.compareTo(c) == 0) {
				pw.println("-1");
				pw.flush();
				break;
			}
			
			if (i.remainder(new BigInteger(t + "")).compareTo(new BigInteger("0")) == 0) {
				pw.println(i);
				pw.flush();
				break;
			}
			
			i = i.add(new BigInteger("1"));
		}
		
		br.close();
		pw.close();
	}

}