function Greetings()
{
var currentdt = new Date();
var currenthour= currentdt.getHours();
if (currenthour < 12)
   {
   document.write("Good Morning!!");
   }
else if (currenthour > 12 && currenthour < 17) 
   {
   document.write("Good Afternoon!!");
   }
else if(currenthour > 17 && currenthour < 20) 
   {
   document.write("Good Evening!!");
   }
else
   {
   document.write("Good Night!!");
   }
}