#include<iostream>
#include<vector>
#include<algorithm>
using namespace std;

template <class Q>
Q median(vector<Q> v)
{
	typedef typename vector<Q>::size_type vec_sz;

	vec_sz size=v.size();
	if(size==0)
		throw domain_error("median of an empty vector");

	sort(v.begin(),v.end());

	vec_sz mid=size/2;

	return size%2==0?(v[mid]+v[mid-1])/2:v[mid];
}

int main()
{
	vector<double> v;
	for(int i=0;i<10;++i)
		v.push_back(i);
	cout<<median(v)<<endl;
	return 0;
}