#include <bits/stdc++.h>
using namespace std;
#define FOR(i, a, b) for(int i = (a); i <= (b); ++i)
#define FORD(i, a, b) for(int i = (a); i >= (b); --i)
#define sz(a) (int)(a).size()
#define all(a) (a).begin(), (a).end()
#define bit(s, i) (((s) >> (i)) & 1)
#define ii pair <int, int>
#define fi first
#define se second
#define ll long long
#define eb emplace_back
#define pb push_back
#define __builtin_popcount __builtin_popcountll
template <class X, class Y>
bool maximize(X &x, Y y) {
if(x < y) {
x = y;
return true;
}
return false;
}
template <class X, class Y>
bool minimize(X &x, Y y) {
if(x > y) {
x = y;
return true;
}
return false;
}
void solve();
int32_t main() {
#define task "test"
if(fopen(task".inp", "r")){
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
cin.tie(0)->sync_with_stdio(0);
int tc = 1; //cin >> tc;
FOR(i, 1, tc){
solve();
}
}
const int N=2e5+5;
const ll INF=1e18;
int n,pre[N],nxt[N]; ll a[N]; bool del[N];
priority_queue<pair<ll,int>> pq;
void solve() {
cin>>n;
FOR(i,1,n) cin>>a[i];
a[0]=a[n+1]=-INF;
FOR(i,1,n) pre[i]=i-1, nxt[i]=i+1, pq.emplace(a[i],i);
ll res=0;
FOR(i,1,(n+1)/2){
auto [val,id]=pq.top(); pq.pop();
while(del[id]) id=pq.top().se, val=pq.top().fi, pq.pop();
res+=val;
a[id]=-a[id]+a[pre[id]]+a[nxt[id]];
pq.emplace(a[id],id);
del[pre[id]]=del[nxt[id]]=true;
nxt[pre[pre[id]]]=id;
pre[nxt[nxt[id]]]=id;
pre[id]=pre[pre[id]];
nxt[id]=nxt[nxt[id]];
cout<<res<<'\n';
}
}
