#include <bits/stdc++.h>
// #include <boost/multiprecision/cpp_int.hpp>
using namespace std;

#define all(a) (a).begin(), (a).end()
#define rall(a) (a).rbegin(), (a).rend()
#define MIN(a) *std::min_element((a).begin(), (a).end())
#define MAX(a) *std::max_element((a).begin(), (a).end())
#define SUM(a) std::accumulate((a).begin(), (a).end(), 0LL)
#define REP(i, n) for (int (i) = 0; (i) < (n); (i)++)
#define RREP(i, n) for (int (i) = (n)-1; (i) >= 0; (i)--)
#define FOR(i, m, n) for (int (i) = (m); (i) < (n); i++)
#define FORR(i, m, n) for (int (i) = (n)-1; (i) >= (m); i--)
#define debug(x) std::cerr << #x << " = " << x << '\n'
// #define int long long

using ll = long long;
using ull = unsigned long long;
using ld = long double;
using vl = std::vector<long long>;
using vvl = std::vector<std::vector<long long>>;
// using bint = boost::multiprecision::cpp_int;
// using rat = boost::rational<bint>;

constexpr int inf = (1 << 30) - 1;
constexpr long long INF = 1LL << 60;
constexpr double eps = 1e-9;

inline void ios_() {std::cin.tie(nullptr); std::ios::sync_with_stdio(false);}
template<typename T> inline T Div(const T& a, const T& b) {return (a + b - 1) / b;}
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;}

template<typename T>
inline void finish(const T& msg) {
    std::cout << msg << std::endl;
    std::exit(0);
}

template<typename T>
long long binarySearch(long long ng, long long ok, const T& fn) {
    while (std::abs(ok - ng) > 1) {
        long long mid = (ok + ng) / 2;
        if (fn(mid)) ok = mid;
        else ng = mid;
    }
    return ok;
}

struct ModInt {
    long long value;
    static constexpr long long mod = 1e9+7;
    // static constexpr long long mod = 998244353;

    constexpr ModInt(long long v = 0) : value(((v % mod) + mod) % mod) {}

    constexpr ModInt pow(long long n) const {
        long long x = value, res = 1;
        while (n > 0) {
            if (n & 1) {
                res = res * x % mod;
            }
            x = x * x % mod;
            n >>= 1;
        }
        return ModInt(res);
    }

    constexpr ModInt inverse() const {
        return pow(mod - 2);
    }

    constexpr ModInt operator-() const {
        return ModInt((mod - value) % mod);
    }

    constexpr ModInt& operator+=(const ModInt& a) {
        value += a.value;
        value %= mod;
        return *this;
    }

    constexpr ModInt& operator-=(const ModInt& a) {
        value += (-a).value;
        value %= mod;
        return *this;
    }

    constexpr ModInt& operator*=(const ModInt& a) {
        value *= a.value;
        value %= mod;
        return *this;
    }

    constexpr ModInt& operator/=(const ModInt& a) {
        return (*this) *= a.inverse();
    }

    constexpr ModInt operator+(const ModInt& a) const {
        return ModInt(*this) += a;
    }

    constexpr ModInt operator-(const ModInt& a) const {
        return ModInt(*this) -= a;
    }

    constexpr ModInt operator*(const ModInt& a) const {
        return ModInt(*this) *= a;
    }

    constexpr ModInt operator/(const ModInt& a) const {
        return ModInt(*this) /= a;
    }

    constexpr bool operator==(const ModInt& a) const {
        return value == a.value;
    }

    constexpr bool operator!=(const ModInt& a) const {
        return value != a.value;
    }

    friend std::istream& operator>>(std::istream& is, ModInt& a) {
        long long v;
        is >> v;
        a = v;
        return is;
    }

    friend std::ostream& operator<<(std::ostream& os, const ModInt& a) {
        os << a.value;
        return os;
    }

    static ModInt factorial(int n) {
        static std::vector<ModInt> fact(1 << 18);

        if (fact.size() <= n) fact.resize(n + 1);

        if (n < 0) return 0;
        if (n == 0) return 1;
        if (fact[n] != 0) return fact[n];

        return fact[n] = factorial(n - 1) * n;
    }

    static ModInt combin(int n, int k) {
        if (n < 0 || k < 0 || n < k) return 0;
        return factorial(n) / (factorial(k) * factorial(n - k));
    }
};

using mint = ModInt;

#include <vector>
#include <deque>
#include <queue>
#include <algorithm>
using ll = long long;

struct Graph {
    struct Edge {
        int from;
        int to;
        ll cost;
        Edge(int a, ll b) : to(a), cost(b) {}
        Edge(int a, int b, ll c) : from(a), to(b), cost(c) {}
    };

    int N;  //頂点数
    std::vector<std::vector<Edge>> edges;   //隣接リスト
    std::vector<ll> dist;   //ノードの深さ
    std::vector<int> deg;   //入次数

    Graph(int n) : N(n), edges(n), dist(n, INF), deg(n, 0) {}

    void connect(int a, int b, ll c) {   //辺を追加
        edges[a].emplace_back(Edge(a, b, c));
        deg[b]++;
    }

    bool visited(int v) {
        return dist[v] < INF;
    }

    void resetDist() {
        for(int i=0; i<N; i++) {
            dist[i] = INF;
        }
    }

    void dfs(int p, int v, ll d) {    //深さ優先探索
        if(visited(v)) return;

        dist[v] = d;

        for(const Edge& e : edges[v]) {
            if(e.to == p) continue;
            dfs(v, e.to, d + e.cost);
        }
    }

    void bfs(int v) {        //幅優先探索
        std::queue<Edge> que;
        for(const Edge& e : edges[v]) {
            que.push(e);
            dist[e.to] = e.cost;
        }

        dist[v] = 0;

        while(!que.empty()) {
            int u = que.front().to;
            ll d = que.front().cost;
            que.pop();

            for(const Edge& e : edges[u]) {
                if(!visited(e.to)) {
                    que.push(Edge(e.from, e.to, d + e.cost));
                    dist[e.to] = d + e.cost;
                }
            }
        }
    }

    ll diameter() {  //木の直径を求める
        static ll res = INF;
        if(res != INF) return res;  //計算済みの場合

        dfs(-1, 0, 0);  //頂点0からの最遠頂点vを求める
        int v = std::max_element(dist.begin(), dist.end()) - dist.begin();

        resetDist();

        dfs(-1, v, 0);  //vからの最遠頂点を求める

        return res = *std::max_element(dist.begin(), dist.end());   //この2頂点間の距離が直径
    }

    void dijkstra(int start) {   //ダイクストラ法
        dist[start] = 0;

        auto fn = [](const Edge& a, const Edge& b){return a.cost > b.cost;};
        std::priority_queue<Edge, std::vector<Edge>, decltype(fn)> que(fn);

        for(const Edge& e : edges[start]) que.push(e);

        while(!que.empty()) {
            auto v = que.top().to;
            auto d = que.top().cost;
            que.pop();

            if(visited(v)) continue;
            else dist[v] = d;
            
            for(const Edge& e : edges[v]) {
                if(dist[e.to] == INF) {
                    que.push(Edge(e.from, e.to, e.cost + d));
                }
            }
        }
    }

    bool BellmanFord(int start) {    //ベルマンフォード法 (負の閉路がある場合はtrueを返す)
        dist[start] = 0;
        for(int i = 0; i < N; i++) {
            for(int j = 0; j < N; j++) {
                for(const Edge& e : edges[j]) {
                    if(visited(j) && dist[j] + e.cost < dist[e.to]) {
                        if(i == N-1) return true;  //N回目にも更新があるなら負の閉路が存在
                        dist[e.to] = dist[j] + e.cost;
                    }
                }
            }
        }
        return false;
    }

    std::vector<int> topologicalSort() { //トポロジカルソート
        std::queue<int> que;
        for(int i = 0; i < N; i++) {
            if(deg[i] == 0) que.push(i);
        }

        std::vector<int> result;

        while(!que.empty()) {
            auto v = que.front();
            que.pop();
            result.push_back(v);
            for(const Edge& e : edges[v]) {
                deg[e.to]--;
                if(deg[e.to] == 0) que.push(e.to);
            }
        }
        
        return result;
    }

    std::deque<int> findCycle() {
        std::vector<int> status(N, 0);
        std::deque<int> hist, result;

        for(int i = 0; i < N; i++) {
            int r = findCycleDfs(-1, i, hist);
            if(r == -1) continue;

            while(!hist.empty()) {
                int v = hist.back();
                result.push_front(v);
                hist.pop_back();
                if(v == r) break;
            }
            break;
        }

        return result;
    }

    int findCycleDfs(int p, int v, std::deque<int>& hist) {
        static std::vector<int> status(N, 0);
        status[v] = 1;
        hist.push_back(v);

        for(const Edge& e : edges[v]) {
            if(e.to == p || status[e.to] == 2) {
                continue;
            }
            if(status[e.to] == 1) {
                return e.to;
            }
            int r = findCycleDfs(v, e.to, hist);
            if(r != -1) return r;
        }

        hist.pop_back();
        status[v] = 2;
        return -1;
    }

    ll solve(int q){
        vector<int> ord(N);
        REP(i, N) ord[i] = i;

        sort(all(ord), [&](int a, int b){return dist[a] > dist[b];});
        ll ans = INF;

        REP(i, N){
            int start = ord[i];
            if(deg[start] > 0) continue;

            auto fn = [](const pair<ll,int>& a, const pair<ll,int>& b){return a.first > b.first;};

            priority_queue<pair<ll,int>,vector<pair<ll,int>>,decltype(fn)> que(fn);
            REP(j, i+1){
                if(deg[ord[j]] == 0) que.push({dist[ord[j]], ord[j]});
            }

            ll x = 0;

            REP(j, q){
                if(que.empty()){
                    x = INF;
                    break;
                }
                auto p = que.top();
                que.pop();
                for(const Edge& e : edges[p.second]){
                    deg[e.to]--;
                    if(deg[e.to] == 0){
                        que.push({dist[e.to], e.to});
                    }
                }
                chmax(x, p.first);
            }

            chmin(ans, x - dist[start]);
        }
        return ans;
    }
};

struct MatrixGraph : Graph {
    MatrixGraph(int n) : Graph(n) {
        for(int i = 0; i < n; i++) {
            for(int j = 0; j < n; j++) {
                edges[i].emplace_back(Edge(i, j, (i == j ? 0 : INF)));
            }
        }
    }

    void connect(int a, int b, ll c) {
        edges[a][b].cost = c;
    }

    void WarshallFloyd() {
        for(int k = 0; k < N; k++) {
            for(int i = 0; i < N; i++) {
                for(int j = 0; j < N; j++) {
                    ll d = edges[i][k].cost + edges[k][j].cost;
                    if(d < edges[i][j].cost) {
                        edges[i][j].cost = d;
                    }
                }
            }
        }
    }
};

struct GridGraph : Graph {
    int H, W;
    std::vector<std::vector<bool>> grid;
    std::vector<int> dx, dy;

    GridGraph(int h, int w) : Graph(h*w), H(h), W(w), grid(h, std::vector<bool>(w, false)) {
        dx = {1, 0, -1, 0, 1, 1, -1, -1};
        dy = {0, 1, 0, -1, 1, -1, 1, -1};
    }

    void setGrid(int x, int y, bool b) {
        grid[x][y] = b;
    }

    bool out(int x, int y) {
        return (x < 0 || x >= H || y < 0 || y >= W);
    }

    int to1D(int x, int y) {
        return x * W + y;
    }

    void connectAll(bool diagonal) {
        for(int x = 0; x < H; x++) {
            for(int y = 0; y < W; y++) {
                if(!grid[x][y]) continue;

                for(int k = 0; k < (diagonal ? 8 : 4); k++) {
                    int nx = x + dx[k], ny = y + dy[k];
                    if(out(nx, ny) || !grid[nx][ny]) continue;
                    connect(to1D(x, y), to1D(nx, ny), 1);
                }
            }
        }
    }
};

signed main() {
    ll n, k, q;
    cin >> n >> k >> q;

    Graph G(n);
    REP(i, n){
        cin >> G.dist[i];
    }

    REP(i, n){
        FOR(j, -(k-1), k){
            if(i + j < 0 || i + j >= n) continue;
            if(G.dist[i] < G.dist[i+j]) G.connect(i, i+j, 1);
        }
    }

    cout << G.solve(q) << endl;

    return 0;
}
