TheWireUs-Day3

#include <bits/stdc++.h>

#define ll long long

using namespace std;

int main()
{
    ll n, ans = -1e18;
    cin >> n;
    vector<pair<ll, ll>> v(n);
    for (ll i = 0; i < n; i++)
    {
        cin >> v[i].first;
        v[i].second = i + 1;
    }
    stack<pair<ll, ll>> S1, S2;
    vector<ll> a, b;

    for (ll i = 0; i < n; i++)
    {
        while (!S1.empty() && S1.top().first >= v[i].first)
        {
            S1.pop();
        }
        if (S1.empty())
        {
            a.push_back(0);
        }
        else
        {
            a.push_back(S1.top().second);
        }
        S1.push(v[i]);
    }

    for (ll i = n - 1; i >= 0; --i)
    {
        while (!S2.empty() && S2.top().first >= v[i].first)
        {
            S2.pop();
        }
        if (S2.empty())
        {
            b.push_back(n + 1);
        }
        else
        {
            b.push_back(S2.top().second);
        }
        S2.push(v[i]);
    }

    reverse(b.begin(), b.end());

    for (ll i = 0; i < n; i++)
    {
        ans = max(ans, v[i].first * (b[i] - a[i] - 1));
    }
    cout << ans << "\n";

    return 0;
}