#pragma GCC optimize("O3")
#include <bits/stdc++.h>
#define ll long long
#define str string
#define pb push_back
#define pf push_front
#define in insert
#define all(v) v.begin(),v.end()
const int sz=1000000,INF=1000000000;
using namespace std;
void solve()
{
ll n,num,ans;
cin>>n;
vector<ll>nums,numsC;
for(int i=0;i<n;i++)
{
cin>>num;
nums.pb(num);
}
while(nums.size()!=1)
{
numsC.clear(),numsC.pb((nums[0]+nums[1])/2);
for(int i=2;i<nums.size();i++)
{
numsC.pb(nums[i]);
}
nums=numsC;
}
ans=nums[nums.size()-1];
cout<<ans;
}
int main()
{
ios_base::sync_with_stdio(false);
cin.tie(nullptr),cout.tie(nullptr);
ll t=1;
//cin>>t;
while(t--)
{
solve();
}
}
