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

#define INF 1234567890
#define ll long long

int N;
int A[100101];

double f(double X)
{
	double ret = 0;
	for(int i=1; i<=N; i++)
	{
		ret += X + A[i] - min(1.0*A[i], X+X);
	}
	ret /= N;

	return ret;
}

int main()
{
	ios::sync_with_stdio(0); cin.tie(0);
	cin.exceptions(ios::badbit | ios::failbit);
	cin >> N;
	for(int i=0; i<N; i++)
		cin >> A[i];
	sort(A, A+N);

	cout << setprecision(12) << fixed;
	cout << f(A[N/2]/2.0) << "\n";
	return 0;
}
#include <iostream>
#include <fstream>
#include <set>
#include <map>
#include <string>
#include <vector>
#include <queue>
#include <deque>
#include <stack>
#include <functional>
#include <algorithm>
#include <climits>
#include <cmath>
#include <iomanip>
using namespace std;
#define ll long long int
#define rep(i,n) for( int i = 0; i < n; i++ )
#define rrep(i,n) for( int i = n; i >= 0; i-- )
#define REP(i,s,t) for( int i = s; i <= t; i++ )
#define RREP(i,s,t) for( int i = s; i >= t; i-- )
#define dump(x)  cerr << #x << " = " << (x) << endl;
#define INF 2000000000
#define mod 1000000007
#define INF2 1000000000000000000
#define int long long
int gcd(int a, int b) {
    if(a < b) return gcd(b, a);
    if(b == 0) return a;
    return gcd(b, a % b);
}
signed main(void)
{
    cin.tie(0);
    ios::sync_with_stdio(false);
    int N; cin >> N;
    int a = 1;
    REP(i, 2, 30) {
        a = a * i / gcd(a, i);
    }
    //REP(i, 2, 30) cout << (a + 1) % i << endl;
    cout << a + 1 << endl;
    return 0;
}
