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:
//package CF;
import java.io.*;
import java.math.BigInteger;
import java.util.*;
public class F {
    public static void main(String[] args) throws Exception {
	Scanner bf = new Scanner(System.in);
	PrintWriter out = new PrintWriter(System.out);
	int n = bf.nextInt();
	BigInteger t = BigInteger.valueOf(bf.nextInt());
	boolean flag = false;
	BigInteger bt = BigInteger.valueOf(10).pow(n);
	for (BigInteger b = BigInteger.valueOf(10).pow(n-1); b.compareTo(bt) < 0 && !flag; b = b.add(BigInteger.ONE))
	{
            if(b.mod(t).equals(BigInteger.ZERO))
            {
        	out.println(b.toString());
        	flag = true;
            }
	}
	if(!flag)
	    out.println(-1);
	out.flush();
	out.close();
    }
    static class Scanner 
    {
	StringTokenizer st;
	BufferedReader br;

	public Scanner(InputStream s){	br = new BufferedReader(new InputStreamReader(s));}

	public String next() throws IOException 
	{
	    while (st == null || !st.hasMoreTokens()) 
		st = new StringTokenizer(br.readLine());
	    return st.nextToken();
	}

	public int nextInt() throws IOException {return Integer.parseInt(next());}

	public long nextLong() throws IOException {return Long.parseLong(next());}

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

	public double nextDouble() throws IOException
	{
	    String x = next();
	    StringBuilder sb = new StringBuilder("0");
	    double res = 0, f = 1;
	    boolean dec = false, neg = false;
	    int start = 0;
	    if(x.charAt(0) == '-')
	    {
		neg = true;
		start++;
	    }
	    for(int i = start; i < x.length(); i++)
		if(x.charAt(i) == '.')
		{
		    res = Long.parseLong(sb.toString());
		    sb = new StringBuilder("0");
		    dec = true;
		}
		else
		{
		    sb.append(x.charAt(i));
		    if(dec)
			f *= 10;
		}
	    res += Long.parseLong(sb.toString()) / f;
	    return res * (neg?-1:1);
	}

	public boolean ready() throws IOException {return br.ready();}
    }

}