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.*;
import java.io.*;

public class Solution {
  public void solve(FastReader in, PrintWriter pw) {
    int n = in.nextInt();
    int t = in.nextInt();

    if (n == 1 && t == 10) {
      pw.print("-1");
      return;
    }

    if (t == 10) {
      pw.print(1);
      for (int i = 0; i < n - 1; i++) {
        pw.print(0);
      }
    } else {
      pw.print(t);
      for (int i = 0; i < n - 1; i++) {
        pw.print(0);
      }
    }
  }

  public static void main(String[] args) throws IOException {
    FastReader in = new FastReader();
    PrintWriter pw = new PrintWriter(System.out);
    new Solution().solve(in, pw);
    pw.flush();
    pw.close();
  }

  private void ln(String str) {
    System.out.println(str);
  }
}

class FastReader
{
  BufferedReader br;
  StringTokenizer st;

  public FastReader()
  {
    br=new BufferedReader(new InputStreamReader(System.in));
  }

  public String next()
  {
    if(st==null || !st.hasMoreElements())
    {
      try {
        st=new StringTokenizer(br.readLine());
      } catch(Exception e) {
        throw new RuntimeException(e);
      }
    }
    return st.nextToken();
  }

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

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