program primer;

var
  n,i,m: integer;
  rez:real;
begin;
  ReadLn(n);
  rez:=1;
  m:=1;
  for i:=1 to n-1 do begin
    m:=m*(-1);
    rez:=rez+m/(i+1)
  end;
  writeln(rez:4:2);
end.