POJ 1939

#include<iostream>
#include<iomanip>
#define MAXN 10000
using namespace std;

double point[MAXN][2];

int main()
{
    //freopen("acm.acm","r",stdin);
    int num;
    int i;
    while(cin>>num)
    {
        cin>>point[0][0]>>point[0][1];
        cout<<num<<" ";
        for(i = 1; i < num; ++ i)
        {
            cin>>point[i][0]>>point[i][1];
            cout<<setiosflags(ios::fixed)<<setprecision(6)<<(point[i][0]+point[i-1][0])/2.0<<" "<<(point[i][1]+point[i-1][1])/2.0<<" ";
        }
        cout<<setiosflags(ios::fixed)<<setprecision(6)<<(point[i-1][0]+point[0][0])/2.0<<" "<<(point[i-1][1]+point[0][1])/2.0<<endl;
    }
}