#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const ll INF = 1e9+7;
const ll MOD = 998244353;
typedef pair<ll,ll> ii;
#define iii pair<ll,ii>
#define f(i,a,b) for(ll i = a;i < b;i++)
#define pb push_back
#define vll vector<ll>
#define F first
#define S second
#define all(x) (x).begin(), (x).end()
///I hope I will get uprating and don't make mistakes
///I will never stop programming
///sqrt(-1) Love C++
///Please don't hack me
///@TheofanisOrfanou Theo830
///Think different approaches (bs,dp,greedy,graphs,shortest paths,mst)
///Stay Calm
///Look for special cases
///Beware of overflow and array bounds
///Think the problem backwards
///Training
int main(void){
ios_base::sync_with_stdio(0);
cin.tie(0);
ll n;
cin>>n;
vll arr(n);
f(i,0,n){
cin>>arr[i];
}
while(n != 1){
ll sum = 1e18;
f(i,0,n-1){
sum = min(sum,arr[i] + arr[i+1]);
}
f(i,0,n-1){
if(arr[i] + arr[i+1] == sum){
arr.erase(arr.begin() + i);
arr.erase(arr.begin() + i);
arr.insert(arr.begin() + i,sum / 2);
}
}
n--;
}
cout<<arr[0]<<"\n";
}
