program pr;
var y:real;
n,m,i:integer;
begin
writeln('vv n');
readln(m);
n:=1;
i:=1;
y:=1-(1/n);
if m=1 then writeln('y=',y)
else
begin
repeat
i:=1+1;
n:=n*i;
if odd(i)=true then y:=y-(1/n) else y:=y+(1/n);
until i=m;
writeln('y=',y);
end;
end.