program t1039;
type
  arr=array[1..2]of integer;

var
  max:longint;
  cc,x,n:integer;
  t:arr;
  Q,happy:array[1..6000]of arr;

procedure Qsort(l,r:integer);
var
  i,j:integer;
begin
  i:=l; j:=r; x:=Q[(l+r)div 2,1];
  repeat
    while Q[i,1]<x do i:=i+1;
    while Q[j,1]>x do j:=j-1;
    if i<=j then begin
      t:=Q[i]; Q[i]:=Q[j]; Q[j]:=t;
      i:=i+1; j:=j-1;
    end;
  until i>j;
  if i<r then Qsort(i,r);
  if l<j then Qsort(l,j);
end;

procedure read_data;
var
  i:integer;
begin
  fillchar(happy,sizeof(happy),-1);
  readln(n);
  for i:=1 to n do readln(happy[i,1]);
  cc:=0;
  repeat
    cc:=cc+1;
    readln(Q[cc,2],Q[cc,1]);
  until (Q[cc,1]=0)and(Q[cc,2]=0);
  cc:=cc-1;
  Qsort(1,cc);
end;

function search(now:integer):integer;
var
  l,r,x:integer;
begin
  l:=1; r:=cc; x:=0;
  while l<=r do
    if Q[(l+r)div 2,1]=now then begin
      x:=(l+r)div 2;
      break;
    end else if Q[(l+r)div 2,1]>now then r:=(l+r) div 2-1
      else l:=(l+r) div 2+1;
  while (Q[x-1,1]=now)and(x-1>0) do x:=x-1;
  search:=x;
end;

procedure recursion(now:integer);
var
  x:integer;
begin
  x:=search(now); happy[now,2]:=0;
  while (x>0)and(Q[x,1]=now)and(x<=n) do begin
    if happy[Q[x,2],2]<0 then recursion(Q[x,2]);
    happy[now,1]:=happy[now,1]+happy[Q[x,2],2];
    happy[now,2]:=happy[now,2]+happy[Q[x,2],1];
    x:=x+1;
  end;
  if happy[now,1]<happy[now,2] then happy[now,1]:=happy[now,2];
  if happy[now,1]>max then max:=happy[now,1];
end;

procedure doit;
var
  i:integer;
begin
  max:=0;
  for i:=1 to n do if happy[i,2]<0 then recursion(i);
end;

procedure write_data;
begin
  write(max);
end;

begin
  read_data;
  doit;
  write_data;
end.

Can you explain me the problem more public???


I don't understand it !!




Thanks  !!!