readln(a);
   b:=0;
   if a>=0 then
   for i:=1 to a do begin
   b:=b+i;
   end
   else
   for i:=1 downto a do begin
   b:=b+i;
   end;
   writeln(b);

Edited by author 13.12.2012 00:05

Why not check that the number is positive or negative. You can simply like this: for i := 1 to a do begin
b : = (b + i;
end. Change and try it. Should earn. Good luck :) !

I may be mistaken, but the program is not true, namely, in the test, when the input number 0 (a = 0), the output of your number will be 0 instead of 1 .. And this is just a linear program ... that is the sum of an arithmetic progression .. Sorry for my English :)