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.util.Arrays;
import java.util.LinkedList;

public class CFTest68 {

	static BufferedReader br;
	static LinkedList<String> tokList;
	static {
		br = new BufferedReader(new InputStreamReader(System.in));
		tokList = new LinkedList<String>();
	}

	public static void main(String[] args) throws IOException {

		int arr[]=readIntArr();
		int n=arr[0];
		int t=arr[1];
		arr=new int[n];
		br.close();
		
		if(t<10){
			for(int i=0;i<n;i++){
				System.out.print(t);
			}
			println("");
		}
		else if(n==1){
			System.out.println(-1);
		}else{
			System.out.print(1);
			for(int i=1;i<n;i++){
				System.out.print(0);
			}
			println("");
		}

	}

	static void print(String s){
		System.out.print(s);
	}
	
	static void println(String s){
		System.out.print(s);
	}
	
	static int nextInt() throws IOException {
		return Integer.parseInt(nextTok());
	}

	static long nextLong() throws IOException {
		return Long.parseLong(nextTok());
	}

	static double nextDouble() throws IOException {
		return Double.parseDouble(nextTok());
	}

	static String nextTok() throws IOException {
		if (tokList.size() == 0) {
			String[] strTok = br.readLine().split(" ");
			for (int i = 0; i < strTok.length; i++) {
				tokList.add(strTok[i]);
			}
		}
		return tokList.removeFirst();
	}

	static public String readLine() throws IOException {
		return br.readLine();

	}

	static public long readLong() throws IOException {
		return Long.parseLong(br.readLine());
	}

	static public int readInt() throws IOException {
		return Integer.parseInt(br.readLine());
	}

	static public int[] readIntArr() throws IOException {
		String[] str = br.readLine().split(" ");
		int arr[] = new int[str.length];
		for (int i = 0; i < arr.length; i++)
			arr[i] = Integer.parseInt(str[i]);
		return arr;
	}

	static public double[] readDoubleArr() throws IOException {
		String[] str = br.readLine().split(" ");
		double arr[] = new double[str.length];
		for (int i = 0; i < arr.length; i++)
			arr[i] = Double.parseDouble(str[i]);
		return arr;
	}

	static public long[] readLongArr() throws IOException {
		String[] str = br.readLine().split(" ");
		long arr[] = new long[str.length];
		for (int i = 0; i < arr.length; i++)
			arr[i] = Long.parseLong(str[i]);
		return arr;
	}

	static public double readDouble() throws IOException {
		return Double.parseDouble(br.readLine());
	}
}