t=input('請輸入時間t：');  
%density_max=input('請輸入：');  


global 
global  

if(t<=0)
          natural_condition(t);
           
           
  elseif(t>=0&t<=linght_on_time)
      
    red_light_on(t);
         
       
   elseif(t>linght_on_time&t<=time_d)
       
       green_light_on(t);
     
    elseif(t>time_d&t<=time_u)
       
     jam_disappearance(t);
           
   elseif(t>time_u&t<recover_time)
       
      catch_up(t);
           
   elseif(t>=recover_time)
        recovery(t);
           
        
    end