program PascalGuru;
function fact(n: integer): longint;
begin
if n = 1 then
fact := 1
else
fact := fact(n - 1) * n;
end;
var
n, i: integer;
rez: real;
begin
write('N= ');
readln(n);
rez := 1;
for i := 1 to n do
if odd(i) then
rez := rez - (1 / fact(i))
else
rez := rez + (1 / fact(i));
writeln('Otvet: ', rez:0:4);
readln;
end.