Problem:
Score : 700 points

Problem Statement

We have N gemstones labeled 1 through N.

You can perform the following operation any number of times (possibly zero).

Select a positive integer x, and smash all the gems labeled with multiples of x.

Then, for each i, if the gem labeled i remains without getting smashed, you will receive a_i yen (the currency of Japan).
However, a_i may be negative, in which case you will be charged money.

By optimally performing the operation, how much yen can you earn?

Constraints

All input values are integers.

1 \leq N \leq 100

|a_i| \leq 10^9

Input

Input is given from Standard Input in the following format:

N
a_1 a_2 ... a_N

Output

Print the maximum amount of money that can be earned.

Sample Input 1

6
1 2 -6 4 5 3

Sample Output 1

12

It is optimal to smash Gem 3 and 6.

Sample Input 2

6
100 -100 -100 -100 100 -100

Sample Output 2

200

Sample Input 3

5
-1 -2 -3 -4 -5

Sample Output 3

0

It is optimal to smash all the gems.

Sample Input 4

2
-1000 100000

Sample Output 4

99000

Solution in Pascal (FPC 2.6.2) (judge verdict: Wrong Answer)

var
  x,y,z:array[0..1000] of int64;
  a,b,c,e,n:longint;d:int64;
begin
  read(n);
  for a:=1 to n do
    begin
      read(x[a]);
      if x[a]<0 then begin
       b:=b+1;
               y[b]:=a;
               end;
    end;
  for a:=b downto 1 do
    begin
      c:=2;d:=x[y[a]];
      while c*y[a]<=100 do
        begin
          if z[c*y[a]]=0 then d:=d+x[c*y[a]];
          c:=c+1;
        end;
      if d<0 then for e:=1 to c do
               z[e*y[a]]:=1;
   end; d:=0;
   for a:=1 to n do
     if z[a]=0 then d:=d+x[a];
     writeln(d);
     end.