记录编号	294918	评测结果	AAAAAAAAAA
题目名称	[LOL2000] 回文词	最终得分	100
用户昵称	转瞬の电流	是否通过	通过
代码语言	Pascal	运行时间	2.244 s
提交时间	2016-08-12 21:11:01	内存使用	43.10 MiB

program hwc;
var
i,j,k,m,n,s:longint;
a,b:ansistring;
f:array[0..5001,0..5001]of integer;
begin
assign(input,'palin.in');
assign(output,'palin.out');
reset(input);
rewrite(output);
readln(n);
readln(a);
for i:=1 to n do
b:=b+a[n-i+1];
for i:=1 to n do
 begin
 f[0,i]:=0;
 f[i,0]:=0;
 end;
m:=0;
for i:=1 to n do
 for j:=1 to n do
 if a[i]=b[j] then f[i,j]:=f[i-1,j-1]+1 else
 if f[i-1,j]>f[i,j-1] then f[i,j]:=f[i-1,j]
  else f[i,j]:=f[i,j-1];
  {for i:=1 to n do
  begin
  for j:=1 to n do
  write(f[i,j],' ');
  writeln;
  end;}
s:=0;
for i:=1 to n-1 do
 if f[i,n-i]>=m then begin m:=f[i,n-i];
 if a[i]<>a[i+1] then s:=1; end;
k:=n-2*m-s;
{writeln(k);
writeln(s,' ',a[s],' ',a[s+1],' ',a[s-1]);

if (a[s]<>a[s+1])or(a[s]<>a[s-1]) then k:=n-2*m-1;}
if s<0 then s:=0;
writeln(k);
close(input);
close(output);
end.