Var
  n,s,k,i             :integer;
  t                   :char;
  a                   :array[0..1001] of boolean;
  b                   :array[0..1001] of integer;

procedure writt(x,y:integer);
Var
  i                   :integer;
begin
  for i:=x to y do
    write(ord(a[i]));
end;

procedure add;
Var
  i,p                 :integer;
begin
  if k=0 then
  begin
    writt(1,s);
    write(0);
  end
  else
  begin
    b[n]:=0;
    for i:=n-1 downto 0 do
      b[i]:=b[i+1]+ord(a[i+1]);
    if k+b[0]>=(n+1) then {add 0}
    begin
      p:=-1;
      repeat inc(p);
      until (k+b[p]) mod (n+1)=0;
      writt(1,p); write(0);
      writt(p+1,s);
    end
    else
    begin
      p:=-1;
      repeat inc(p);
      until (k+p+b[p]) mod (n+1)=0;
      writt(1,p-1);
      write(1);
      writt(p,s);
    end;
  end;
end;

procedure chn;
begin
  if k=0 then
    writt(1,n)
  else
  begin
    writt(1,k-1);
    if not a[k] then while true do;
    write(0);
    writt(k+1,n);
  end
end;

procedure del;
Var
  i,p                 :integer;
begin
  if k=0 then
    writt(1,n)
  else
  begin
    b[n+1]:=0;
    for i:=n downto 0 do
      b[i]:=b[i+1]+ord(a[i+1]);
    p:=0;
    repeat inc(p);
    until (k-b[p]-p*(ord(a[p]))+n+1) mod (n+1)=0;
    writt(1,p-1);
    writt(p+1,n+1);
  end;
end;

begin
  readln(n);
  while not eof do
  begin
    s:=0;
    while (not eoln) and (not eof) do
    begin
      read(t);
      if (ord(t)=48) or (ord(t)=49) then begin
        inc(s);
        a[s]:=ord(t)=49;
      end;
    end;
    readln;
    k:=0;
    for i:=1 to s do
      if a[i] then
        k:=(k+i) mod (n+1);
    if s =n-1 then
      add
      else if s=n then
        chn
        else if s=n+1 then
          del;
   if (s>=n-1) and (s<=n+1) then
      writeln;
  end;
end.

Hi there,

After 20Wa, i see my programs answers right for tescases, sepeartely
(i.e. one senteces per test.) but suddenly i saw that my program after
10test for n=5
which in 2nd sentence 1100-->11100
in 10th i again write 1100 and saw incredible!:
answer of 1100 was 01100!!!!

where was my mistake?!!

Just in Add Procedure i read value of a[n] but sentence was only
n-1bit and nth value was by previouses tests!
so just i insert this line after begin of add procedure:
A[N]:=False;

And Got AC :P

wish best times for you
Aidin_n7@hotmail.com