    ,    . 
         .     :
1. " " -   "" ,  #1!
2. "" -    ""!
3. " " -   "",  #2! 
4. "  " -       !
5. " " -   "",  #3!
            -.
---
 ,     " "      "" ! 
      300 ,     1000.
---
  ,   21   -  ,   ,
     ,     . 
---
             ""    
"  ,  ".   ,     ,  ,    
   ,  .