#include<cstdio>
#include<cstring>
#include<algorithm>
#include<cmath>
using namespace std;
const int maxn=1000+5;
struct Point
{
	double x,y;
	Point(){}
	Point(double x,double y):x(x),y(y){}
}P[maxn];

int main()
{
	int n;
	while(scanf("%d",&n)==1)
	{
		for(int i=0;i<n;++i) scanf("%lf%lf",&P[i].x,&P[i].y);
		P[n]=P[0];
		printf("%d",n);
		for(int i=0;i<n;++i)
			printf(" %.6lf %.6lf",(P[i].x+P[i+1].x)/2, (P[i].y+P[i+1].y)/2);
		printf("\n");
	}
	return 0;
}