Algorithm for a pizza shop, Which one is better??

 Console.WriteLine("You are selected Small size, We'll send you :)");        

             Console.WriteLine("Price: " + price + "$");

put these lines of code after the end of switch method if amount is not equal to zero.

your's friends code:

  case 1: 
 price += 5;   
 break;               
  case 2:
   price += 5; 
 goto case 1;   
   case 3:  
 price += 5; 
   goto case 1;
why to do looping again and again put the direct amount case 2 and case 3 without going case 1 
again. if use this code change case 3 if amount is 15 RS then change it price += 10;