#include <bits/stdc++.h>
#define pb emplace_back
#define SZ(x) ((int)x.size())
#define fi first
#define se second
#define FOR(i, a, b) for (int i = a, _b = b; i <= _b; ++i)
#define FORD(i, a, b) for (int i = a, _b = b; i >= _b; --i)
#define FORLL(i, a, b) for (ll i = a, _b = b; i <= _b; ++i)
#define FORDLL(i, a, b) for (ll i = a, _b = b; i >= _b; --i)
#define all(x) x.begin(), x.end()
#define uni(x) sort(all(x)), x.erase(unique(all(x)), x.end())
using namespace std;
typedef long long ll;
typedef unsigned long long ull;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define dbg(...) debug(#__VA_ARGS__, __VA_ARGS__)
template<typename T>
void __prine_one(const char *&s, const T &x)
{
while (*s == ' ') ++s;
const char *p = s;
int bal = 0;
while (*s)
{
if (*s == '(') ++bal;
else if (*s == ')') --bal;
else if (*s == ',' && bal == 0) break;
++s;
}
cerr.write(p, s - p) << " = " << x;
if (*s == ',')
{
cerr << " , ";
++s;
}
}
template<typename... Args>
void debug(const char *s, Args... args)
{
cerr << "[ ";
int dummy[] = {0, (__prine_one(s, args), 0)...};
(void)dummy;
cerr << " ]\n\n";
}
template<class X>
bool maximize(X &a, const X &b)
{
if (b > a)
{
a = b;
return true;
}
return false;
}
template<class X>
bool minimize(X &a, const X &b)
{
if (b < a)
{
a = b;
return true;
}
return false;
}
// --------------------------------------------------------------------------------------------
constexpr int maxn = 1e6 + 3;
int n, root[maxn];
ll a[maxn], dp[maxn];
// --------------------------------------------------------------------------------------------
void readInput()
{
cin >> n;
FOR(i, 1, n)
cin >> a[i];
}
namespace Lichao
{
int cur_version;
struct Line
{
ll a, b;
ll eval(ll x) {return a * x + b;}
int l, r;
Line()
{
a = 0; b = 1e18;
l = r = 0;
}
Line(ll a, ll b) : a(a), b(b)
{
}
};
struct Node
{
Line f;
int l, r;
};
Node seg[maxn * 19];
int build(int l, int r)
{
if (l > r) return 0;
int mid = l + r >> 1;
++cur_version;
seg[cur_version].l = build(l, mid - 1);
seg[cur_version].r = build(mid + 1, r);
return mid;
}
int upd(int id, int l, int r, Line f)
{
if (l > r) return 0;
int mid = l + r >> 1;
++cur_version;
seg[cur_version] = seg[id];
if (f.eval(mid) < seg[cur_version].f.eval(mid))
swap(seg[cur_version].f, f);
if (f.a < seg[id].f.a)
seg[cur_version].l = upd(seg[cur_version].l, l, mid - 1, f);
else if (f.a > seg[id].f.a)
seg[cur_version].r = upd(seg[cur_version].r, mid + 1, r, f);
return cur_version;
}
ll get(int id, int l, int r, int pos)
{
ll res = seg[id].f.eval(pos);
int mid = l + r >> 1;
if (mid != pos)
{
if (pos < mid && seg[id].l) minimize(res, get(seg[id].l, l, mid - 1, pos));
if (pos > mid && seg[id].r) minimize(res, get(seg[id].r, mid + 1, r, pos));
}
return res;
}
}
void solve()
{
root[0] = Lichao :: build(1, n);
vector<int> st;
st.push_back(0);
a[0] = 1e18;
FOR(i, 1, n)
{
while (st.size() && a[st.back()] <= a[i]) st.pop_back();
int lst = st.back();
root[i] = Lichao :: cur_version;
++root[i];
Lichao :: seg[root[i]] = Lichao :: seg[root[lst]];
dp[i] = dp[lst] + a[i] * (i - lst);
minimize(dp[i], Lichao :: get(root[i], 1, n, i));
Lichao :: upd(root[i], 1, n, Lichao :: Line(a[i], dp[i] - i * a[i]));
st.push_back(i);
}
cout << dp[n];
}
signed main()
{
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
#define TASK "TEST"
if (fopen(TASK".INP", "r"))
{
freopen(TASK".INP", "r", stdin);
freopen(TASK".OUT", "w", stdout);
}
readInput();
solve();
return 0;
}
