class MovingAverage {
public:
    /** Initialize your data structure here. */
    MovingAverage(int size) : windowSize(size) {}

    double next(int val) {
        while(data.size() >= windowSize)
        {
          sum -= data.front();
          data.pop_front();
        }
        data.push_back(val);
        sum += val;
        return sum/double(data.size());
    }

private:
  std::deque<double> data;
  int windowSize = 0;
  int sum = 0;
};