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.*;
import java.util.*;

public class SolutionA {

   BufferedReader in;
   StringTokenizer str;
   PrintWriter out;
   String SK;

   String next() throws IOException {
      while ((str == null) || (!str.hasMoreTokens())) {
         SK = in.readLine();
         if (SK == null) {
            return null;
         }
         str = new StringTokenizer(SK);
      }
      return str.nextToken();
   }

   String nexts() throws IOException {
      return in.readLine();
   }

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

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

   long nextLong() throws IOException {
      return Long.parseLong(next());
   }
   public static void main(String[] args) throws IOException {
      new SolutionA().run();
   }

   void run() throws IOException {
      in = new BufferedReader(new InputStreamReader(System.in));
      out = new PrintWriter(System.out);
      solve();
      out.close();
   }
   void solve() throws IOException {
      int n = nextInt();
      int t=nextInt();
      if(t==10){
         if(n==1){
            out.print(-1);
            return;
         }
         out.print(1);
         for (int i = 0; i < n-1; i++) {
            out.print(0);
         }
         return;
      }
      for (int i = 0; i < n; i++) {
         out.print(t);
      }
      out.println();
      

   }

  
}