program CrazyCoder;

uses
  crt;

const
  rad = 3.7;

var
  dug, res: real;

begin
  clrscr;
  writeln('Ââåäèòå äëèíó äóãè: ');
  readln(dug);
  res := rad * rad * dug / 2;
  writeln('Ïëîùàäü ñåêòîðà ðàâíà: ', res:0:2);
end.