GPT答：

7i24.cn

```cpp
#include <iostream>
#include <algorithm>

int main() {
    int N, M;
    std::cin >> N >> M;

    int* candies = new int[N];
    for (int i = 0; i < N; i++) {
        std::cin >> candies[i];
    }

    std::sort(candies, candies + N);

    int sum = 0;
    for (int i = 0; i < N / M; i++) {
        sum += candies[N - (i * M) - 1];
    }

   delete[] candies;

   std::cout << sum << std::endl;

   return 0;
}
```