I think my program is correct,but it always gets WA,why?
Here is my program:

program U1048;
const
  digits=100000000;
var
  n1,n2:array[0..200000] of longint;
  i,j,n,a,b:longint;
  s:string;
begin
  readln(n);
  n1[0]:=0;
  for j:=n div 8*8+1 to n do begin
      readln(a,b);
      n1[1]:=n1[1]*10+a;
      n2[1]:=n2[1]*10+b;
  end;
  inc(n1[1],n2[1]);
  for i:=1 to n div 8 do begin
    for j:=1 to 8 do begin
      readln(a,b);
      n1[i+1]:=n1[i+1]*10+a;
      n2[i+1]:=n2[i+1]*10+b;
    end;
    inc(n1[i+1],n2[i+1]);
  end;
  for i:=n div 8+1 downto 1 do
    if n1[i]>=digits then begin
      dec(n1[i],digits);
      inc(n1[i-1]);
    end;
  j:=0;
  while (n1[j]=0)and(j<200000) do inc(j);
  if n1[j]=0 then writeln(0)
  else begin
    write(n1[j]);
    for i:=j+1 to n div 8+1 do begin
      str(n1[i],s);
      while length(s)<8 do s:='0'+s;
      write(s);
    end;
    writeln;
  end;
end.