#include<vector>

#include<iostream>

using namespace std;

struct point{int x;int z;};

vector<point> datas;

int oldest_ind=0,newest_ind=0;

int window=50;

void addd(point p)

{

if(datas.size()<window)

datas.push_back(p);

else

{newest_ind = oldest_ind;datas[oldest_ind++]=p;}

newest_ind=oldest_ind-1;

if(oldest_ind==window) {newest_ind=window-1;oldest_ind=0;}

}

int main()

{

for(int i=0;i<101;i++)

{

struct point p;

p.x =i;p.z=100;

addd(p);

}

std::cout<<datas.size()<<endl;

for(int i=0 ; i<datas.size();i++)

std::cout<<datas[i].x<<",";

std::cout<<endl<<datas[oldest_ind].x<<endl;//ind the oldest one , (ind-1) the newest one

std::cout<<endl<<datas[newest_ind].x<<endl;

}