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 C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i,a) for(int i=0;i<(a);i++)
const ll MOD=1000000007;

ll A[111];

int main(){
  int N; cin>>N;
  rep(i,N){
    cin>>A[i+1];
    if(i+1>N/2&&A[i+1]<0) A[i+1]=0;
  }
  for(int i=N/2;i>=1;i--) if(A[i]<0){
    ll sum=0;
    for(int j=i;j<=N;j+=i) sum+=A[j];
    if(sum<=0){
      for(int j=i;j<=N;j+=i) A[j]=0;
    }
  }
  ll ans=0;
  rep(i,N) ans+=A[i+1];
  cout<<ans<<endl;
  return 0;
}