记录编号	22176	评测结果	AAAAAAAAAA
题目名称	拯救	最终得分	100
用户昵称	王者自由	是否通过	通过
代码语言	Pascal	运行时间	0.145 s
提交时间	2010-11-17 15:42:50	内存使用	0.23 MiB

program savey;
type number=record
    s:array[1..5000]of longint;
    len:longint;
  end;
var A,B:array[1..10100]of longint;
    n,i:longint;
    x,sum:number;
procedure add(a,b:number; var c:number);
var i,max:longint; d:number;
begin
  fillchar(d.s,sizeof(d.s),0);
  max:=a.len; if b.len>a.len then max:=b.len;
  for i:=1 to max do d.s[i]:=a.s[i]+b.s[i];
  d.len:=max;
  for i:=1 to max do
  begin
    d.s[i+1]:=d.s[i+1]+d.s[i] div 10;
    d.s[i]:=d.s[i] mod 10;
  end;
  if d.s[max+1]>0 then inc(d.len);
  c:=d; 
end; 
procedure mul(a:number; var c:number);
var i:longint; d:number;
begin
  fillchar(d.s,sizeof(d.s),0);
  for i:=1 to a.len do d.s[i]:=d.s[i]+a.s[i]*2;
  for i:=1 to a.len+1 do
  begin
    d.s[i+1]:=d.s[i+1]+d.s[i] div 10;
    d.s[i]:=d.s[i] mod 10;
  end;
  d.len:=a.len+1;
  while d.s[d.len]=0 do dec(d.len);
  c:=d;
end;
begin
  assign(input,'savey.in'); reset(input);
  assign(output,'savey.out'); rewrite(output);
  readln(n);
  for i:=n downto 1 do read(A[i]);
  B[1]:=A[1];
  for i:=2 to n do B[i]:=A[i] xor B[i-1];//格雷码解码成二进制
  sum.len:=1; sum.s[1]:=0;
  x.s[1]:=1; x.len:=1;
  for i:=n downto 1 do
  begin
    if B[i]=1 then add(x,sum,sum);
    mul(x,x);
  end; //二进制转十进制
  for i:=sum.len downto 1 do write(sum.s[i]);
  writeln;
  close(input); close(output);
end.