I submit this problem and got WA?
Wazzup???

Var
  N, J, Sum: Integer;
  I: Word;
Begin
  Read (N);
  Sum:= 0;
  J:= 1;
  If N >= 1 Then Begin
    For I:= I to N do
      Sum:= Sum + I;
  End
  Else
    For I:= 1 to 2 + Abs (N) do Begin
      Sum:= Sum + J;
      Dec (J);
    End;
  WriteLn (Sum);
End.

> Var
>   N, J, Sum: Integer;
>   I: Word;
Your variables are too small. Just change 'Word' and 'Integer'
into 'LongInt', and then you will be right.