I wrote a program for 1068 "Sum" - the code is really very
easy. Judge program says always me "wrong answer". Where is
my mistake? Could anybody help me?

program p;
var i,n:integer;
    res:longint;
begin
  read(n);
  res := 0;
  if (n >=1) then
     for i:=1 to n do res := res + i
  else
     for i:=1 downto n do res := res + i;
  write(res);
end.

What was the problem with your program?
Please tell me, 'cause as you can see, Ricardo have the same problem.

I could only tell you about the right programme.
because my English is very bad.
Bellow is the answer.
var
 n:longint;
begin
  readln(n);
  writeln((1+n)*(abs(n-1)+1)div 2);
end.