const n = 3; const x = 1;

var s, c: double;

var a: integer;

begin

s := x;

a := -1;

for var i:= 1 to n do begin

for var j:= 1 to i do

c := c * x;

a := -a;

s := s + a*c/(i * i);

c := x;

end;

write(s);

end.