#include <bits/stdc++.h>
#if __has_include(<atcoder/all>)
#include <atcoder/all>
using namespace atcoder;
using mint = modint998244353;
// using mint = modint1000000007;
#endif
//#pragma GCC target("avx2")
//#pragma GCC optimize("Ofast")
//#pragma GCC optimize("unroll-loops")
using namespace std;

inline void scan(int &a) { cin >> a; }
inline void scan(unsigned int &a) { cin >> a; }
inline void scan(long long &a) { cin >> a; }
inline void scan(unsigned long long &a) { cin >> a; }
inline void scan(float &a) { cin >> a; }
inline void scan(double &a) { cin >> a; }
inline void scan(long double &a) { cin >> a; }
inline void scan(char &a) { cin >> a; }
inline void scan(string &a) { cin >> a; }
inline void scan(vector<bool> &vec) { for (int i = 0; i < int(vec.size()); i++) { int a; scan(a); vec[i] = a; } }

template<typename T> inline void scan(vector<T> &vec);
template<typename T, size_t size> inline void scan(array<T, size> &vec);
template<typename T> inline void scan(deque<T> &deq);
template<typename T, typename U> inline void scan(pair<T, U> &p);

template<typename T> inline void scan(vector<T> &vec) { for (auto &i : vec) scan(i); }
template<typename T, size_t size> inline void scan(array<T, size> &vec) { for (auto &i : vec) scan(i); }
template<typename T> inline void scan(deque<T> &deq) { for (auto &i : deq) scan(i); }
template<typename T, typename U> inline void scan(pair<T, U> &p) { scan(p.first); scan(p.second); }
template<typename T> inline void scan(T &a) { cin >> a; }
inline void read() { }
template<typename T, typename... U> inline void read(T &a, U &...b) { scan(a); read(b...); }

inline void write(const int &a) { cout << a; }
inline void write(const unsigned int &a) { cout << a; }
inline void write(const long long &a) { cout << a; }
inline void write(const unsigned long long &a) { cout << a; }
inline void write(const float &a) { cout << a; }
inline void write(const double &a) { cout << a; }
inline void write(const long double &a) { cout << a; }
inline void write(const char &a) { cout << a; }
inline void write(const string &a) { cout << a; }

template<typename T> inline void write(const vector<T> &vec);
template<typename T, size_t size> inline void write(const array<T, size> &vec);
template<typename T> inline void write(const deque<T> &deq);
template<typename T, typename U> inline void write(const pair<T, U> &p);

template<typename T> inline void write(const vector<T> &vec) {
    for (int i = 0; i < int(vec.size()); i++) {
        if (i) write(' ');
        write(vec[i]);
    }
}

template<typename T, size_t size> inline void write(const array<T, size> &vec) {
    for (int i = 0; i < int(vec.size()); i++) {
        if (i) write(' ');
        write(vec[i]);
    }
}

template<typename T> inline void write(const deque<T> &deq) {
    for (int i = 0; i < int(deq.size()); i++) {
        if (i) write(' ');
        write(deq[i]);
    }
}

template<typename T, typename U> inline void write(const pair<T, U> &p) {
    write(p.first);
    write(' ');
    write(p.second);
}

template<typename T> inline void write(const T &a) { cout << a; }

inline void print() { cout << '\n'; }
template<typename T> inline void print(const T &a) { write(a); cout << '\n'; }
template<typename T, typename... U> inline void print(const T &a, const U &...b) {
    write(a);
    ((cout << ' ', write(b)), ...);
    write('\n');
}
template<typename T> inline void debug_impl(const char *name, const T &value) {
    cerr << name << " = ";
    write(value);
    cerr << '\n';
}

template<typename T, typename ... U> inline void debug_impl(const char *names, const T &value, const U &...values) {
    const char *comma = strchr(names, ',');
    cerr.write(names, comma - names);
    cerr << " = ";
    write(value);
    cerr << ", ";
    while (*++comma == ' ');
    debug_impl(comma, values...);
}

using ll = long long;
using ld = long double;
using ull = unsigned long long;
using pii = pair<int, int>;
using pll = pair<ll, ll>;
template<typename T> using pq = priority_queue<T>;
template<typename T> using pq_g = priority_queue<T, vector<T>, greater<T>>;

#define overload3(a, b, c, d, ...) d
#define overload4(a, b, c, d, e, ...) e
#define rep1(n) for (ll i = 0; i < (n); i++)
#define rep2(i, n) for (ll i = 0; i < (n); i++)
#define rep3(i, a, b) for (ll i = (a); i < (b); i++)
#define rep4(i, a, b, c) for (ll i = (a); i < (b); i += (c))
#define rep(...) overload4(__VA_ARGS__, rep4, rep3, rep2, rep1)(__VA_ARGS__)
#define rrep1(n) for (ll i = (n) - 1; i >= 0; i--)
#define rrep2(i, n) for (ll i = (n) - 1; i >= 0; i--)
#define rrep3(i, a, b) for (ll i = (b) - 1; i >= (a); i--)
#define rrep4(i, a, b, c) for (ll i = (a) + ((b) - (a) - 1) / (c) * (c); i >= (a); i -= (c))
#define rrep(...) overload4(__VA_ARGS__, rrep4, rrep3, rrep2, rrep1)(__VA_ARGS__)
#define all1(v) (v).begin(), (v).end()
#define all2(v, n) (v).begin(), (v).begin() + (n)
#define all3(v, a, b) (v).begin() + (a), (v).begin() + (b)
#define all(...) overload3(__VA_ARGS__, all3, all2, all1)(__VA_ARGS__)
#define rall(v) (v).rbegin(), (v).rend()
#define UNIQUE(v) (v).erase(unique((v).begin(), (v).end()), (v).end())
#define NP next_permutation
#define endl '\n'
#define INT(...) int __VA_ARGS__; read(__VA_ARGS__);
#define LL(...) long long __VA_ARGS__; read(__VA_ARGS__);
#define ULL(...) unsigned long long __VA_ARGS__; read(__VA_ARGS__);
#define STR(...) string __VA_ARGS__; read(__VA_ARGS__);
#define CHAR(...) char __VA_ARGS__; read(__VA_ARGS__);
#define LD(...) long double __VA_ARGS__; read(__VA_ARGS__);
#define VEC(type, name, size) vector<type> name(size); read(name);
#define VV(type, name, h, w) vector<vector<type>> name(h, vector<type>(w)); read(name);
#ifdef LOCAL
#define debug(...) debug_impl(#__VA_ARGS__, __VA_ARGS__)
#else
#define debug(...) ((void)0)
#endif

inline void Yes(bool a = true) { cout << (a ? "Yes" : "No") << endl; }
inline void No(bool a = true) { cout << (a ? "No" : "Yes") << endl; }
inline void YES(bool a = true) { cout << (a ? "YES" : "NO") << endl; }
inline void NO(bool a = true) { cout << (a ? "NO" : "YES") << endl; }
inline void Takahashi(bool a = true) { cout << (a ? "Takahashi" : "Aoki") << endl; }
inline void Alice(bool a = true) { cout << (a ? "Alice" : "Bob") << endl; }
inline void Possible(bool a = true) { cout << (a ? "Possible" : "Impossible") << endl; }

constexpr int INF = 1001001001;
constexpr ll LINF = 4004004004004004004LL;
constexpr ld pi = 3.14159265358979323846;
constexpr ld eps = 1e-9;
constexpr int dx[8] = { 1, 0, -1, 0, 1, -1, -1, 1 };
constexpr int dy[8] = { 0, 1, 0, -1, 1, 1, -1, -1 };

ll modPow(ll a, ll n, ll mod = LINF) { ll ret = 1; ll x = a % mod; while (n) { if (n & 1) ret = ret * x % mod; x = x * x % mod; n >>= 1; } return ret; }
int topbit(int x) { return (x == 0 ? -1 : 31 - __builtin_clz(x)); }
int topbit(ll x) { return (x == 0 ? -1 : 63 - __builtin_clzll(x)); }
int lowbit(int x) { return (x == 0 ? -1 : __builtin_ctz(x)); }
int lowbit(ll x) { return (x == 0 ? -1 : __builtin_ctz(x)); }
int popcount(int x) { return __builtin_popcount(x); }
ll popcount(ll x) { return __builtin_popcountll(x); }
ll isqrt(ll x) { ll n = sqrtl(x); while ((n + 1) * (n + 1) <= x) n++; while (n * n > x) n--; return n; }
template<typename T> T floor(T a, T b) { return a / b - (a % b && (a ^ b) < 0); }
template<typename T> T ceil(T a, T b) { return floor(a + b - 1, b); }
template<typename T> T bmod(T a, T b) { return a - b * floor(a, b); }
template<typename T> pair<T, T> divmod(T a, T b) { return { floor(a, b), a - b * floor(a, b) }; }
template<typename T> auto MIN(const vector<T> &a) { return *min_element(all(a)); }
template<typename T> auto MAX(const vector<T> &a) { return *max_element(all(a)); }
template<typename T> auto SUM(const vector<T> &a) { return accumulate(all(a), T(0)); }
template<typename T> bool chmin(T &a, const T &b) { if (a > b) { a = b; return true; } return false; }
template<typename T> bool chmax(T &a, const T &b) { if (a < b) { a = b; return true; } return false; }

void cincout() {
    ios::sync_with_stdio(false);
    cin.tie(nullptr);
    cout << fixed << setprecision(15);
}

template<typename T>
struct AdvancedMultiset {
private:
    int n;
    vector<vector<T>> data;
    vector<T> sum;
    T sum_all;
    static constexpr int BUCKET_RATIO = 50, REBUILD_RATIO = 170;

    vector<T> get_all() const {
        vector<T> ret;
        ret.reserve(n);
        for (auto &v : data) ret.append_range(v);
        return ret;
    }

    void modify() {
        build(get_all(), true);
    }

    pair<int, int> position(T x) const {
        int i = 0;
        while (i + 1 < int(data.size()) && data[i].back() < x) i++;
        int j = lower_bound(data[i].begin(), data[i].end(), x) - data[i].begin();
        return {i, j};
    }

public:
    AdvancedMultiset() : n(0), data(1), sum(1), sum_all(T(0)) {}

    void build(vector<T> v, bool sorted = false) {
        n = v.size();
        if (!sorted) sort(v.begin(), v.end());
        int K = sqrt(n / BUCKET_RATIO) + 1;
        data.resize(K);
        sum.resize(K, T(0));
        for (int i = 0; i < K; i++) {
            int l = n * i / K, r = n * (i + 1) / K;
            data[i] = vector<T>(v.begin() + l, v.begin() + r);
            sum[i] = accumulate(data[i].begin(), data[i].end(), T(0));
        }
    }

    void insert(T x) {
        if (!n) {
            data[0].push_back(x);
            n = 1, sum[0] += x, sum_all += x;
            return;        
        }

        auto [i, j] = position(x);
        data[i].insert(data[i].begin() + j, x);
        n++, sum[i] += x, sum_all += x;
        if (int(data[i].size()) > int(data.size()) * REBUILD_RATIO) modify();
    }

    void erase(T x) {
        if (!n) return;
        auto [i, j] = position(x);
        if (j == int(data[i].size()) || data[i][j] != x) return;
        data[i].erase(data[i].begin() + j);
        n--, sum[i] -= x, sum_all -= x;
        if (data[i].empty() && data.size() > 1) {
            data.erase(data.begin() + i);
            sum.erase(sum.begin() + i);
        }
    }

    bool contains(T x) const {
        if (!n) return false;
        auto [i, j] = position(x);
        return j < int(data[i].size()) && data[i][j] == x;
    }

    int count(T x) const {
        if (!n) return 0;
        auto [i, j] = position(x);
        return upper_bound(data[i].begin(), data[i].end(), x) - data[i].begin() - j;
    }

    // return {kth smallest, sum of elements before it}
    pair<T, T> get_kth_smallest(int k) const {
        assert(0 <= k && k <= n);
        if (k == n) {
            return {numeric_limits<T>::max(), sum_all};
        }
        T s = 0;
        for (int i = 0; i < int(data.size()); i++) {
            if (int(data[i].size()) <= k) {
                k -= data[i].size();
                s += sum[i];
            } else {
                for (int j = 0; j < k; j++) s += data[i][j];
                return {data[i][k], s};
            }
        }
        assert(false);
    }

    // return {kth largest, sum of elements after it}
    pair<T, T> get_kth_largest(int k) const {
        assert(0 <= k && k <= n);
        if (k == n) {
            return {numeric_limits<T>::min(), sum_all};
        }
        auto [x, s] = get_kth_smallest(n - 1 - k);
        return {x, sum_all - s - x};

    }

    // return {count, sum} (l <= x < r)
    pair<T, T> range(T l, T r) const {
        assert(l <= r);
        if (!n) return {0, 0};
        int cnt = 0;
        T s = 0;
        for (int i = 0; i < int(data.size()); i++) {
            auto &v = data[i];
            if (v.back() < l) continue;
            if (r <= v.front()) break;

            if (l <= v.front() && v.back() < r) {
                cnt += int(v.size());
                s += sum[i];
            } else {
                int L = lower_bound(data[i].begin(), data[i].end(), l) - data[i].begin();
                int R = lower_bound(data[i].begin(), data[i].end(), r) - data[i].begin();
                cnt += R - L;
                for (int j = L; j < R; j++) s += data[i][j];
            }
        }
        return {cnt, s};
    }

    T min() const {
        assert(n);
        return data.front().front();
    }

    T max() const {
        assert(n);
        return data.back().back();
    }

    size_t size() const {
        return size_t(n);
    }

    bool empty() const {
        return !n;
    }

    void dump() {
        for (auto &v : data) for (auto &x : v) cout << x << " ";
        cout << '\n';
    }
};

void solve() {
    LL(N, K, X);
    VEC(ll, A, N);
    AdvancedMultiset<ll> s;
    ll ans = -LINF;
    for (int i = 0; i < N; i++) {
        s.insert(A[i]);
        chmax(ans, s.get_kth_largest(min(ll(i + 1), K)).second - X * (i + 1));
    }
    print(ans);
}

int main() {
    cincout();
    int t = 1;
    // cin >> t;
    while (t--) solve();
    return 0;
}