#include <vector>

class FixedAllocator {
 public:
  FixedAllocator(size_t chunk_size, size_t page_size);
  void *Allocate();
  void Deallocate(void *value);

 private:
  size_t chunk_size;
  size_t page_size;
  std::vector<std::vector<unsigned char>> pool;
  size_t free_memory = 0;
  unsigned char *memory;
};

FixedAllocator::FixedAllocator(size_t chunk_size, size_t page_size) {
  this->chunk_size = chunk_size;
  this->page_size = page_size;
}

void *FixedAllocator::Allocate() {
  if (chunk_size > free_memory) {
    pool.emplace_back(page_size * chunk_size);
    free_memory = pool.back().size();
    memory = &pool.back().front();
  }
  auto front_memory = memory;
  free_memory -= chunk_size;
  memory += chunk_size;
  return front_memory;
}

void FixedAllocator::Deallocate(void *value) {
  auto front_memory = (unsigned char *) value;
  memory = front_memory;
  free_memory += chunk_size;
}