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#include <iostream>
#include <vector>
#include <algorithm>

using namespace std;

vector<int> nodes;
vector<pair<int, int>> edges;
vector<long long> sums;
vector<long long> sumsRev;
vector<int> f_sums;
vector<int> f_sumsRev;
vector<int> e_sums;
vector<int> e_sumsRev;
long long sum = 0;
int f_sum = 0;
int e_sum = 0;


int calcDistance(int from, int to) {
    if (from == 0) {
        return e_sums[to];
    }
    if (to == nodes.size()) {
        return e_sumsRev[from];
    }
    return e_sum - e_sums[from] - e_sumsRev[to];
}

long long calcSum(int from, int to) {
    if (from == 0) {
        return sums[to];
    }
    if (to == nodes.size()) {
        return sumsRev[from];
    }
    return sum - sums[from] - sumsRev[to];
}


struct Node {
    int from;
    int to;
    vector<Node *> children;
};

void updateTree(Node *root, pair<int, int> &edge) {
    Node *node = root;
    while (!node->children.empty()) {
        for (auto &child: node->children) {
            if (child->from <= edge.second && child->to > edge.second) {
                node = child;
                break;
            }
        }
    }

    if (calcSum(node->from, edge.second + 1) >= 0 && calcSum(edge.second + 1, node->to) >= 0) {
        Node *child1 = new Node();
        Node *child2 = new Node();
        child1->from = node->from;
        child1->to = edge.second + 1;
        child2->from = edge.second + 1;
        child2->to = node->to;
        node->children.push_back(child1);
        node->children.push_back(child2);
    }
}

Node *buildTree(int from, int to, vector<pair<int, int>> &edges) {
    Node *root = new Node();
    root->from = from;
    root->to = to;

    for (auto &edge:edges) {
        updateTree(root, edge);
    }

    return root;
}

int calculateDistances(Node *tree) {
    if (tree->children.empty()) {
        return calcDistance(tree->from, tree->to - 1);
    }
    int sum = 0;
    for (auto &child: tree->children) {
        sum += calculateDistances(child);
    }
    return sum;
}

int main() {
    ios_base::sync_with_stdio(0);
    cin.tie(0);

    //------------------------------------------------------------------
    // INPUT READ
    int num;
    cin >> num;
    int elem;

    edges.reserve(num);
    nodes.reserve(num);
    for (int i = 0; i < num; i++) {
        cin >> elem;
        if (elem == 0) {
            if (edges.empty()) {
                continue;
            }
            ++edges.back().first;
        } else {
            edges.emplace_back(1, edges.size());
            nodes.push_back(elem);
        }
    }
    edges.erase(edges.end());

    //------------------------------------------------------------------
    // SUMS CALCULATIONS
    f_sums.push_back(0);
    sums.push_back(0);
    for (int nodeVal : nodes) {
        sum += nodeVal;
        sums.push_back(sum);

        if (nodeVal > 0) f_sum += 1;
        f_sums.push_back(f_sum);
    }

    e_sums.push_back(0);
    for (auto &edgePair : edges) {
        e_sum += edgePair.first;
        e_sums.push_back(e_sum);
    }

    sumsRev.assign(nodes.size() + 1, 0);
    f_sumsRev.assign(nodes.size() + 1, 0);
    long long sumRev = 0;
    int f_sumRev = 0;
    for (int i = nodes.size() - 1; i >= 0; i--) {
        sumRev += nodes[i];
        sumsRev[i] = sumRev;

        if (nodes[i] > 0) f_sumRev += 1;
        f_sumsRev[i] = f_sumRev;
    }


    e_sumsRev.assign(edges.size() + 1, 0);
    int e_sumRev = 0;
    for (int i = edges.size() - 1; i >= 0; i--) {
        e_sumRev += edges[i].first;
        e_sumsRev[i] = e_sumRev;
    }


    sort(edges.rbegin(), edges.rend());

    //------------------------------------------------------------------
    // SOLUTION
    auto root = buildTree(0, nodes.size(), edges);

    cout << calculateDistances(root) << endl;

    return 0;
}