program pizza;
{This works out the cost of a pizza}
{Ronald Begg}
uses Crt;
label extra;
const
     fixedcost = 3.75;
     basecost = 1.55;
     extracost = 0.75;
var
   diameter,area,cost,sellingCost : real;
   ingred : integer;
begin
     clrscr;                            {This block is my title}
     writeln ('------------------');
     writeln ('Pizza Cost Program');
     writeln ('------------------');
     writeln;

{input}
       write ('Diameter of the Pizza(cm): ');
       readln (diameter);
       diameter := diameter /100;   {convert to metres}

       extra:
       write ('Number of extra ingredients: ');
       readln (ingred);
       
       if (ingred > 3) or (ingred < 0) then
       begin
          writeln ('Invalid number of extra ingredients, please enter 0-3');
          goto extra;
       end;

{processing}
       area := pi*sqr(diameter)/4;
       cost := fixedcost + (basecost*area) + (ingred*extracost*area);
       sellingcost := cost * 1.5;

{output}
       writeln;
       writeln;
       writeln ('The total cost of this Pizza is: $',sellingCost:0:2);
       writeln;
       writeln ('Press any key to exit...');
       while not keypressed do;          {Waits for a key to be pressed}
end.