program Project2;

{$APPTYPE CONSOLE}

uses
  SysUtils;

var
y:real;
k,n:integer;
s:real;

function F(k:integer):real;
 begin
  if k<=n then
   begin
    result:= (((k)/(k - 1))*((k)/(k + 1)))*F(k+2);
   end
   else
     result := 1;
 end;



BEGIN
y:=1;

writeln('vvedi n');
readln(n);

writeln(F(2));

s:=1;
k:=2;
writeln('bez recursii');
 repeat
  s:=s*( ((k)/(k - 1)) * ((k)/(k+1)));
  k:=k+2;
 until k>n;
 writeln(s);

readln;
END.