#include <bits/stdc++.h>
using namespace std;

int main()
{
	int N;
	cin >> N;
	vector<int> A( N );
	for( int i = 0; i < N; i++ ) {
		cin >> A[i];
	}

	sort( A.begin(), A.end() );
	double ans = A[N / 2];
	if( N % 2 == 0 ) ans = (double)( A[N / 2] + A[N / 2 - 1] ) / 2;

	cout << fixed << setprecision( 2 ) << ans << endl;
}