#include "bits/stdc++.h"
using namespace std;
#ifdef LOCAL
#include "debug.h"
#else
#define debug(...)
#endif
using ll = long long;
using pii = pair<int, int>;
#define F first
#define S second
#define sz(x) (int)((x).size())
#define all(x) (x).begin(), (x).end()
mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
ll get_rand(ll l, ll r) {
assert(l <= r);
return uniform_int_distribution<ll> (l, r)(rng);
}
const int N = 1e6 + 3;
#pragma once
struct Node{
ll val;
const Node operator + (const Node &other){
Node res;
res.val = max(val, other.val);
return res;
}
};
struct ST{
int n;
vector<Node> st;
Node def = Node(); // default value
void init(int _n){
n = _n;
st.resize(4 * n + 6, def);
}
void _update(int id, int l, int r, int pos, ll val){
if(l == r){
st[id].val = val;
return;
}
int m = (l + r) / 2;
if(l <= pos and pos <= m)
_update(2 * id, l, m, pos, val);
else
_update(2 * id + 1, m + 1, r, pos, val);
st[id] = st[2 * id] + st[2 * id + 1];
}
Node _query(int id, int l, int r, int tl, int tr){
if(l > tr or tl > r)
return def;
if(tl <= l and r <= tr)
return st[id];
int m = (l + r) / 2;
return _query(2 * id, l, m, tl, tr) + _query(2 * id + 1, m + 1, r, tl, tr);
}
Node query(int l, int r){
return _query(1, 1, n, l, r);
}
void update(int pos, ll val){
_update(1, 1, n, pos, val);
}
};
int n;
ll a[N], f[N];
namespace Sub14{
bool valid_input(){
return n <= 1500;
}
void solve(){
ST dak;
dak.init(n);
for(int i = 1; i <= n; ++i)
dak.update(i, a[i]);
memset(f, 0x3f3f3f, sizeof(f));
f[0] = 0;
for(int i = 1; i <= n; ++i)
for(int j = 1; j <= i; ++j)
f[i] = min(f[i], f[j - 1] + 1ll * (n - j + 1) * dak.query(j, i).val);
cout << f[n];
}
}
struct Line {
mutable ll k, m, p;
bool operator<(const Line& o) const { return k < o.k; }
bool operator<(ll x) const { return p < x; }
};
struct LineContainer : multiset<Line, less<>> {
// (for doubles, use inf = 1/.0, div(a,b) = a/b)
static const ll inf = LLONG_MAX;
ll div(ll a, ll b) { // floored division
return a / b - ((a ^ b) < 0 && a % b); }
bool isect(iterator x, iterator y) {
if (y == end()) return x->p = inf, 0;
if (x->k == y->k) x->p = x->m > y->m ? inf : -inf;
else x->p = div(y->m - x->m, x->k - y->k);
return x->p >= y->p;
}
void add(ll k, ll m) {
auto z = insert({k, m, 0}), y = z++, x = y;
while (isect(y, z)) z = erase(z);
if (x != begin() && isect(--x, y)) isect(x, y = erase(y));
while ((y = x) != begin() && (--x)->p >= y->p)
isect(x, erase(y));
}
ll query(ll x) {
assert(!empty());
auto l = *lower_bound(x);
return l.k * x + l.m;
}
};
namespace Sub2{
bool valid_input(){
bool ok = 1;
for(int i = 2; i <= n; ++i)
ok &= (a[i] >= a[i - 1]);
return ok;
}
LineContainer cht;
ll f[N];
void solve(){
f[0] = 1;
cht.add(-n, 0);
for(int i = 1; i <= n; ++i){
f[i] = -cht.query(a[i]);
cht.add(-(n - i), -f[i]);
}
cout << f[n];
}
}
namespace Sub3{
bool valid_input(){
bool ok = 1;
for(int i = n - 1; i >= 1; --i)
ok &= (a[i] >= a[i + 1]);
return ok;
}
ll pref[N];
void solve(){
f[0] = 0;
pref[1] = f[0] + 1ll * n * a[1];
for(int i = 1; i <= n; ++i){
f[i] = pref[i];
pref[i + 1] = min(pref[i], f[i] + 1ll * (n - i) * a[i + 1]);
}
cout << f[n];
}
}
namespace Sub5{
int r[N];
ll mx[N];
LineContainer cht;
void solve(){
int cur = 0;
for(int i = 1; i <= n; ++i){
if(a[cur] < a[i]){
while(cur < i){
cht.add(-(n - cur), -f[cur]);
++cur;
}
}
f[i] = -cht.query(a[cur]);
}
cout << f[n];
}
}
void solve(){
cin >> n;
for(int i = 1; i <= n; ++i)
cin >> a[i];
if(Sub14::valid_input())
Sub14::solve();
else if(Sub2::valid_input())
Sub2::solve();
else if(Sub3::valid_input())
Sub3::solve();
else
Sub5::solve();
}
int32_t main() {
cin.tie(nullptr)->sync_with_stdio(0);
#define task "troll"
if(fopen(task".inp", "r")){
freopen(task".inp", "r", stdin);
freopen(task".out", "w", stdout);
}
int test = 1;
// cin >> test;
for(int i = 1; i <= test; ++i){
// cout << "Case #" << i << ": ";
solve();
}
#ifdef LOCAL
cerr << "\n[Time]: " << 1000.0 * clock() / CLOCKS_PER_SEC << " ms.\n";
#endif
return 0;
}
