                       
                       
      b                
      ab               
      aab              
      aab              
      aab              
      aab              
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
      aaab             
   cccccccccc          
       dd              
       de              
       dd              
       de              
       dd              
       de              
       dd              
       cc              
                       
                       
