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:
/*input
3 7
*/
import java.io.*;
import java.util.*;
import java.math.*;

public class Main {
	public static void main(String []args) throws IOException {
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

		StringTokenizer srt = new StringTokenizer(br.readLine());
		int n = Integer.parseInt(srt.nextToken());
		int t = Integer.parseInt(srt.nextToken());
		
		String s = "", e = "";
		if (n == 1) {s = "1"; e = "10";}
		else {
			for (int i = 1; i<n; i++) s+="0";
			s = "1"+s;
			e = s + "0";
		}
		BigInteger start = new BigInteger(s);
		BigInteger end = new BigInteger(e);
		boolean flag = false;
		for (; start.compareTo(end) == -1; start = start.add(BigInteger.ONE)) {
			BigInteger[] dnr = start.divideAndRemainder(BigInteger.valueOf(t));
			if (dnr[1].equals(BigInteger.ZERO)) {
				flag = true;
				System.out.println(start.toString());
				break;
			}
		}
		if(!flag) System.out.println(-1);

	}
}