ACMNB - ACM
Tác giả: ladpro98
Ngôn ngữ: Pascal
program acmnb;
uses math;
const fi='';
maxN=800004;
type e=record
x,y,s:longint;
end;
var a:array[1..maxN] of e;
n:longint;
procedure input;
var f:text;
i:longint;
begin
assign(f,fi);
reset(f);
readln(f,n);
for i:=1 to n shl 1 do
begin
readln(f,a[i].x,a[i].y);
a[i].s:=a[i].x-a[i].y;
end;
close(f);
end;
procedure swap(i,j:longint);
var t:e;
begin
t:=a[i];
a[i]:=a[j];
a[j]:=t;
end;
procedure sort(l,r:longint);
var p,i,j:longint;
begin
if l>=r then exit;
p:=a[random(r-l+1)+l].s;
i:=l;j:=r;
repeat
while a[i].s<p do inc(i);
while a[j].s>p do dec(j);
if i<=j then
begin
if i<j then swap(i,j);
inc(i);
dec(j);
end;
until i>j;
sort(l,j);
sort(i,r);
end;
procedure cal;
var i,res:longint;
begin
res:=0;
for i:=1 to n do
inc(res,a[i].x);
for i:=n+1 to n shl 1 do
inc(res,a[i].y);
write(res);
end;
begin
input;
sort(1,n shl 1);
cal;
end.