//#include <atcoder/all>
#include<bits/stdc++.h>
using namespace std;
//using namespace atcoder;
using ll = long long;
#define all(A) A.begin(),A.end()
using vll = vector<ll>;
#define rep(i, n) for (long long i = 0; i < (long long)(n); i++)
using Graph = vector<vector<ll>>;
vector<ll> fact, factinv, inv;


int main() {
    ll N;
    cin>>N;
    
    vector<double> A(N);
    rep(i,N)cin>>A[i];
    sort(all(A));
    cout<<(A[N/2]+A[(N-1)/2])/2.0<<endl;
}