记录编号	2305	评测结果	AATTAAAATA
题目名称	[NOI 1999]棋盘分割	最终得分	70
用户昵称	SMXX	是否通过	未通过
代码语言	Pascal	运行时间	3.481 s
提交时间	2008-09-17 21:31:00	内存使用	0.11 MiB

program fd;
var
f1,f2:text;
ans,e:real;
n,i,k,j:integer;
a:array[1..8,1..8]of integer;
b:array[1..15]of record x1,x2,y1,y2:integer; end;

function  min(a,b:real):real;
begin
if a<b then min:=a
       else min:=b;
       end;
function tt:real;
var
r:real;
s,k,h,i:integer;
d:array[1..15]of integer;
begin
for i:= 1to n do begin
  s:=0;
  for k:= b[i].x1 to b[i].x2-1 do
   for h:=b[i].y1 to b[i].y2-1 do
    s:=s+a[k,h];
  d[i]:=s;
  end;
 r:=0;
for i:= 1to n do r:=r+(d[i]-e)*(d[i]-e);
tt:=sqrt(r/n);
end;



procedure main(a:integer);
var
i,j,k:integer;
begin
if a=n then ans:=min(ans,tt) else begin
 for k:=1 to a do begin
   for i:=b[k].x1+1 to b[k].x2-1 do begin
      b[a+1].x1:=i;b[a+1].y1:=b[k].y1;
      b[a+1].x2:=b[k].x2;b[a+1].y2:=b[k].y2;
      b[k].x2:=i;
      main(a+1);
      b[k].x2:=b[a+1].x2;
      end;
   for j:=b[k].y1+1to b[k].y2-1 do begin
      b[a+1].x1:= b[k].x1;b[a+1].y1:=j;
      b[a+1].x2:=b[k].x2;b[a+1].y2:=b[k].y2;
      b[k].y2:=j;
      main(a+1);
      b[k].y2:=b[a+1].y2;
      end;
   end;
 end;
 end;

begin
assign(f1,'division.in');
assign(f2,'division.out');
reset(f1);
rewrite(f2);
readln(f1,n);
for i:= 1to 8 do
 for j:= 1to 8 do begin
 read(f1,a[i,j]);k:=k+a[i,j];
 end;
 e:=k/n;
 ans:=1000000000;
b[1].x1:=1;b[1].y1:=1;
b[1].x2:=9;b[1].y2:=9;
main(1);
writeln(f2,ans:0:3);
close(f1);
close(f2);
end.