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.BufferedReader;
import java.io.IOException;
import java.io.InputStreamReader;
import java.io.PrintWriter;
import java.util.StringTokenizer;
import java.util.Arrays;

public class Cv {
//==========================Solution============================//
	public static void main(String[] args) {
		
		FastScanner in = new FastScanner();
		Scanner input = new Scanner(System.in);
		PrintWriter out = new PrintWriter(System.out);

		int n = input.nextInt();
		int t = input.nextInt();

		if (n == 1 && t == 10) {
			out.println(-1);
		}

		else {
			if (t != 10) {
				for (int i = 0; i < n; i++) {
					out.print(t);
				}
			}

			else {
				out.print(1);
				for	(int i = 0; i < n - 1; i++) {
					out.print(0);
				}
			}
		}
		out.close();
	}
//==============================================================//
	static class FastScanner {
		
		BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
		StringTokenizer st = new StringTokenizer("");
		
		public String next() {
			while (!st.hasMoreElements()) {
				try {
					st = new StringTokenizer(br.readLine());
				} catch (IOException e) {
					e.printStackTrace();
				}
			}
			return st.nextToken();
		}
		
		public String nextLine() {
			String str = "";
			try {
				str = br.readLine();
			} catch (IOException e) {
				e.printStackTrace();
			}
			return str;
		}
		
		byte nextByte() {
			return Byte.parseByte(next());
		}

		short nextShort() {
			return Short.parseShort(next());
		}

		int nextInt() {
			return Integer.parseInt(next());
		}
		
		long nextLong() {
			return java.lang.Long.parseLong(next());
		}
		
		double nextDouble() {
			return Double.parseDouble(next());
		}
	}
}