var cyc2,tm,s1,s2,s,n,k,cyc1:longint;
begin
  read(n);
  read(s1,s2);
  tm:=s1+s2;
  k:=0;
  if tm=9 then inc(k);
  for cyc1:=1 to n-1 do
    begin
      read(s1,s2);
      s:=s1+s2;
      if k=0 then
        begin
          if s<9 then begin write(tm);tm:=s; end;
          if s=9 then inc(k);
          if s>9 then begin write(tm+1);tm:=s-10; end;
        end
      else
         begin
          if s<9 then begin write(tm);for cyc2:= 1 to k do write
(9);tm:=s;k:=0; end;
          if s=9 then inc(k);
          if s>9 then begin write(tm+1);for cyc2:= 1 to k do write
(0); tm:=s-10;k:=0; end;
        end;
    end;
    if k=0 then write(tm) else
         begin if tm<>9 then write(tm); for cyc2:= 1 to k do write
(9);end;
end.

Why don't you try this?
4
9 0
9 0
9 0
1 9
I'm sure that your answer is wrong!
But!
You got AC!
ft......
I have no idea about the test system!

In your example there will be 5 digits and n is only 4.
I've got accepted too in the same ideea