#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
#define MASK(i) (1ULL << (i))
#define GETBIT(mask, i) (((mask) >> (i)) & 1)
#define ALL(v) (v).begin(), (v).end()
ll max(ll a, ll b){return (a > b) ? a : b;}
ll min(ll a, ll b){return (a < b) ? a : b;}
ll LASTBIT(ll mask){return (mask) & (-mask);}
int pop_cnt(ll mask){return __builtin_popcountll(mask);}
int ctz(ull mask){return __builtin_ctzll(mask);}
int logOf(ull mask){return 63 - __builtin_clzll(mask);}
// mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
mt19937_64 rng(69);
ll rngesus(ll l, ll r){return l + (ull) rng() % (r - l + 1);}
template <class T1, class T2>
bool maximize(T1 &a, T2 b){
if (a < b) {a = b; return true;}
return false;
}
template <class T1, class T2>
bool minimize(T1 &a, T2 b){
if (a > b) {a = b; return true;}
return false;
}
template <class T>
void printArr(T& container, string separator = " ", string finish = "\n", ostream &out = cout){
for(auto item: container) out << item << separator;
out << finish;
}
template <class T>
void remove_dup(vector<T> &a){
sort(ALL(a));
a.resize(unique(ALL(a)) - a.begin());
}
const int N = 1e6 + 69;
const ll INF = 1e18 + 69;
int n;
ll a[N];
ll dp[N];
namespace Sub2{
void solve(){
reverse(a + 1, a + n + 1);
memset(dp, 63, sizeof dp);
dp[0] = 0;
for(int i = 1; i<=n; ++i){
ll ma = 0;
for(int j = i; j>=1; --j){
maximize(ma, a[j]);
minimize(dp[i], dp[j-1] + 1LL * ma * i);
}
}
cout << dp[n] << "\n";
exit(0);
}
}
namespace Sub4{
bool check(){
for(int i = 1; i<n; ++i) if (a[i] < a[i+1]) return false;
return true;
}
void solve(){
cout << a[1] * n << "\n";
exit(0);
}
}
namespace Sub6{
struct CHT{
#define Line pair<ll, ll>
vector<Line> a;
vector<double> bubble;
CHT(){
}
double get_intersection(Line a, Line b){
return (double) (b.second - a.second) / (a.first - b.first);
}
void add(Line f){
if (a.size() && a.back().first == f.first) return;
if (a.empty()) {a.push_back(f); return;}
while(bubble.size()){
double x = bubble.back(), y = get_intersection(a.back(), f);
if (x >= y){
a.pop_back(); bubble.pop_back();
}
else break;
}
bubble.push_back(get_intersection(a.back(), f));
a.push_back(f);
}
ll get(ll x){
int idx = lower_bound(ALL(bubble), x) - bubble.begin();
return a[idx].first * x + a[idx].second;
}
};
void solve(){
reverse(a + 1, a + n + 1);
CHT hull_min;
memset(dp, 63, sizeof dp);
dp[0] = 0;
for(int i = n-1; i>=1; --i) maximize(a[i], a[i+1]);
for(int i = 1; i<=n; ++i){
hull_min.add(make_pair(a[i], dp[i-1]));
dp[i] = hull_min.get(i);
}
cout << dp[n] << "\n";
exit(0);
}
}
int main(void){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n;
for(int i= 1; i<=n; ++i) cin >> a[i];
Sub6::solve();
return 0;
}
