#include "bits/stdc++.h"
using namespace std;
#ifdef duc_debug
#include "D:\\debug.h"
#else
#define debug(...)
#endif
const int maxn = 2e5 + 5;
int n, a[maxn];
int pref[maxn], suf[maxn];
bool mark[maxn];
void solve() {
cin >> n;
for(int i = 1; i <= n; ++i) {
cin >> a[i];
if(i > 1) pref[i] = i - 1;
if(i < n) suf[i] = i + 1;
}
priority_queue<pair<long long, int>> pq;
for(int i = 1; i <= n; ++i) {
pq.push(make_pair(a[i], i));
}
long long res = 0;
for(int i = 1; i <= (n + 1) / 2; ++i) {
bool flag = 0;
while(!pq.empty() and !flag) {
pair<long long, int> t = pq.top();
pq.pop();
if(mark[t.second]) continue;
flag = 1;
res += t.first;
int lst = pref[t.second], nxt = suf[t.second];
debug(i, t, lst, nxt, a[t.second]);
a[t.second] = a[lst] + a[nxt] - a[t.second];
mark[lst] = mark[nxt] = 1;
pref[t.second] = pref[pref[t.second]];
suf[t.second] = suf[suf[t.second]];
pref[suf[t.second]] = t.second;
suf[pref[t.second]] = t.second;
pq.push(make_pair(a[t.second], t.second));
}
cout << res << '\n';
}
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
solve();
return 0;
}
