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
  n,i,j,k:longint;x:int64;
  a:array[1..100] of int64;
begin
  read(n);
  for i:=1 to n do
    read(a[i]);
  for k:=1 to trunc(sqrt(n))+1 do
  for i:=n downto 1 do
    begin
      j:=i;x:=0;
      while j<=n do
        begin
          x:=x+a[j];
          j:=j+i;
        end;
      if x<0 then
        begin
          j:=i;
          while j<=n do
            begin
              a[j]:=0;
              j:=j+i;
            end;
        end;
    end;
  x:=0;
  for i:=1 to n do
    x:=x+a[i];
  write(x);
end.