Bzoj1572 [Usaco2009 Open]工作安排Job

var
d,v,heap:array[0..100050] of longint;
n,i,time,cnt,p:longint;
ans:int64;
procedure swap(var a,b:longint);
var t:longint;
begin t:=a;a:=b;b:=t;end;
procedure sort(l,r:longint);
var
i,j,e:longint;
begin
i:=l;j:=r;e:=d[(l+r)>>1];
repeat
while d[i]>e do inc(i);
while e>d[j] do dec(j);
if not (i>j) then
begin
swap(d[i],d[j]);
swap(v[i],v[j]);
inc(i);dec(j);
end;
until i>j;
if l<j then sort(l,j);
if i<r then sort(i,r);
end;
procedure heapup(x:longint);
begin
while ((x>1)and(heap[x]>heap[x>>1])) do
begin
swap(heap[x],heap[x>>1]);
x:=x>>1;
end;
end;
procedure heapdown(x:longint);
var
e:longint;
begin
while ((x<<1<=cnt)and(heap[x<<1]>heap[x])or(x<<1+1<=cnt)and(heap[x<<1+1]>heap[x])) do
begin
if ((x<<1+1<=cnt)and(heap[x<<1+1]>heap[x<<1]))
then e:=x<<1+1
else e:=x<<1;
swap(heap[x],heap[e]);
x:=e;
end;
end;
procedure push(x:longint);
begin
inc(cnt);
heap[cnt]:=x;
heapup(cnt);
end;
procedure poop;
begin
heap[1]:=heap[cnt];
dec(cnt);
heapdown(1);
end;
begin
read(n);
for i:=1 to n do read(d[i],v[i]);
sort(1,n);
time:=1000000000;
cnt:=0;p:=0;ans:=0;
repeat
while ((p+1<=n)and(d[p+1]=time)) do
begin
inc(p);
push(v[p]);
end;
if (cnt>0) then
begin
inc(ans,heap[1]);
poop;
end;
if (cnt=0)and(p<n)
then time:=d[p+1]
else dec(time);
until (p=n)and(cnt=0)or(time=0);
writeln(ans);
end.