var a,n,b,m,l:integer;
    s,s2:string;
begin
while not(eof)do begin
s:='';
readln(n);
  for a:=1 to n do s:=s+' ';
  repeat
  m:=0;
  for b:=1 to n do begin
  if s[b]<>'0' then m:=m+1;
  if m mod 2<>0 then s[b]:='0';
  end;
  l:=0;
  for b:=1 to n do if s[b]<>'0' then l:=l+1;
  until l=1;
  for b:=n downto 1 do if s[b]<>'0' then begin
  writeln(b);
  halt;
    end;
  end;
end.

..........

楼上的签名偶怎么看不懂撒啊?