program berrnulli;

{$APPTYPE CONSOLE}

uses
  SysUtils;

function sochet(n,m:integer):extended;
var i:integer;
    c:extended;
begin
c:=1;
for i:=1 to m do
c:=c*(n-i+1)/i;
sochet:=c
end;
function bernulli(n:integer):extended;
var k:integer;
    s,t:extended;
begin
if n=0 then bernulli:=1
else if n=1 then bernulli:=-0.5
else
 begin
  s:=0;
  for k:=1 to n do
   begin
    t:=bernulli(n-k);
    s:=s+sochet(n+1,k+1)*t;
   end;
  bernulli:=s*(-1)/(n+1);
 end;
if (n>1) and odd(n) then bernulli:=0
end;
var n:integer;
begin
write('n=');
readln(n);
write(bernulli(n):0:10);
readln
end.
end.