import java.util.*;
class MovingAverage {
	private int maxSize;
	private int size;
	private Queue<Integer> data;
    
    /** Initialize your data structure here. */
    public MovingAverage(int size) {
        maxSize = size;
        data = new LinkedList<Integer>();
    }
    
    public double next(int val) {
        if(size >= maxSize)
        	data.poll();
        if(size < maxSize)
        	size++;
        data.offer(val);
        int sum = 0;
        for(Integer k: data) {
        	sum += k;
        }
        return (double) sum / size;
        	
    }
}

/**
 * Your MovingAverage object will be instantiated and called as such:
 * MovingAverage obj = new MovingAverage(size);
 * double param_1 = obj.next(val);
 */
 

太簡單了，沒啥好說的，直接把程式碼貼上過來了