const
p = 3.14;
var
L, S:real;
begin
write('L = '); readln(L);
writeln('S = ', sqr (L / (2 * p)) * pi);
end.
const
p = 3.14;
var
L, S:real;
begin
write('L = '); readln(L);
writeln('S = ', sqr (L / (2 * p)) * pi);
end.