N 16
                                           
                                            
                                                  
                                            25  1997 . N 66
   
                          
              , 
              ,
                   
   
   +----------------------------------------------------------------+
    N                    
   /                              
                                            (,  
                                                     ) 
   +---+-------------+---------------------------------+------------
    1       2                      3                      4     
   +---+-------------+---------------------------------+------------
   1. ;                                
      ;                      
                                   
                          :            
                               1           
                                        
                                    1           
                               1           
                                      2  
                                                
                                    1           
                                            
                                    1       
                               4       
                                                                
   2.                              
                       :                              
                               1           
                                        
                                    1           
                               1           
                                      2  
                                                
                                    1           
                                            
                                    1       
                               4       
                                                                   
      .             ,
         ,     
       .          
      ,               
           ,          ,
      ,  .       
   +----------------------------------------------------------------+