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?

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.

Constraints

• All input values are integers.
• $1 \leq N \leq 100$
• $|a_i| \leq 10^9$

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

见题面 Input 部分

见题面 Output 部分