static int wing=[]()

 {

     std::ios::sync_with_stdio(false);

     cin.tie(NULL);

     return ;

 }();

 class Solution

 {

 public:

     double findMaxAverage(vector<int>& nums, int k)

     {

         int sz=nums.size();

         double maxsum=0.0;

         double cursum=0.0;

         for(int i=;i<k;i++)

             cursum+=nums[i];

         maxsum=cursum;

         for(int j=k;j<sz;j++)

         {

             cursum=cursum-nums[j-k]+nums[j];

             maxsum=max(cursum,maxsum);

         }

         return maxsum/k;

     }

 };