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.math.BigInteger;
	import java.math.*;
	//import java.text.DecimalFormat;
	import java.util.*;
	import java.io.*;

	public class Temp2 {

		public static void main(String[] args) throws IOException
		{
			BufferedReader br = new BufferedReader(new InputStreamReader(System.in));
			StringTokenizer st = new StringTokenizer(br.readLine());
			int n = Integer.parseInt(st.nextToken());
			int tt = Integer.parseInt(st.nextToken());
			BigInteger t = new BigInteger(tt+"");
			BigInteger max = new BigInteger("10");
			BigInteger min = new BigInteger("10");
			max = max.pow(n);
			min = min.pow(n-1);
			boolean found = false;
			BigInteger zero = new BigInteger("0");
			BigInteger one = new BigInteger("1");
			while(min.compareTo(max)==-1)
			{
				if( (min.mod(t)).equals(zero))
				{
					System.out.println(min);
					found=true;
					break;
				}
				min = new BigInteger(min.add(one).toString());
			}
			if(!found)System.out.println(-1);
		}
}