class Main
{
   public static void main(String[] args)
   {
      for (int loop1 = 1; loop1 <= 20; loop1 = loop1 + 1)
      {
         for (int loop2 = 1; loop2 <= 20; loop2 = loop2 + 1)
         {
            System.out.print("OX");
         }
         System.out.println("");
         for (int loop3 = 1; loop3 <= 20; loop3 = loop3 + 1)
         {
            System.out.print("XO");
         }
         System.out.println("");
      }
   }
}