题目描述
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-----
6
1 2 -6 4 5 3
-----Sample Output-----
12
It is optimal to smash Gem 3 and 6.
输入格式
见题面
输出格式
见题面