Program HOC24;
var i,n: integer;
s: real;
begin
write('Nhap N: '); readln(n);
s:=0;
for i:=1 to n do s:=s+1/(i*i*i);
write('S = ',s:6:2);
readln
end.
program TongS;
var
n: Integer;
S: Real;
i: Integer;
begin
write('Nhap n: ');
readln(n);
S := 0;
for i := 1 to n do
begin
S := S + 1/Power(i,3);
end;
writeln('Tong S = ', S:0:2);
readln;
end.