#include <bits/stdc++.h>
using namespace std;
template <typename T>
void DEBUG(T e) {
  if (true == false) return;
  std::cout << e << " ";
}
template <typename T>
void DEBUG(const std::vector<T> &v) {
  if (true == false) return;
  for (const auto &e : v) {
    std::cout << e << " ";
  }
  std::cout << std::endl;
}
template <typename T>
void DEBUG(const std::vector<std::vector<T>> &vv) {
  if (true == false) return;
  for (const auto &v : vv) {
    DEBUG(v);
  }
}
template <class T, class... Ts>
void DEBUG(T d, Ts... e) {
  if (true == false) return;
  DEBUG(d);
  DEBUG(e...);
}
template <class T>
void corner(bool flg, T hoge) {
  if (flg) {
    cout << hoge << endl;
    abort();
  }
}
template <typename T1, typename T2>
inline bool chmax(T1 &a, T2 b) {
  return a < b && (a = b, true);
}
template <typename T1, typename T2>
inline bool chmin(T1 &a, T2 b) {
  return a > b && (a = b, true);
}
template <typename X>
struct SegTree {
  using FX = function<X(X, X)>;
  long long n;
  FX fx;
  const X ex;
  vector<X> dat;
  SegTree(long long n_, FX fx_, X ex_)
      : n(), fx(fx_), ex(ex_), dat(n_ * 4, ex_) {
    long long x = 1;
    while (n_ > x) {
      x *= 2;
    }
    n = x;
  }
  void set(long long i, X x) { dat[i + n - 1] = x; }
  void build() {
    for (long long k = n - 2; k >= 0; k--)
      dat[k] = fx(dat[2 * k + 1], dat[2 * k + 2]);
  }
  void update(long long i, X x) {
    i += n - 1;
    dat[i] = x;
    while (i > 0) {
      i = (i - 1) / 2;
      dat[i] = fx(dat[i * 2 + 1], dat[i * 2 + 2]);
    }
  }
  X query(long long a, long long b) { return query_sub(a, b, 0, 0, n); }
  X query_sub(long long a, long long b, long long k, long long l, long long r) {
    if (r <= a || b <= l) {
      return ex;
    } else if (a <= l && r <= b) {
      return dat[k];
    } else {
      X vl = query_sub(a, b, k * 2 + 1, l, (l + r) / 2);
      X vr = query_sub(a, b, k * 2 + 2, (l + r) / 2, r);
      return fx(vl, vr);
    }
  }
};
void solve(void) {
  long long n, k, q;
  cin >> n >> k >> q;
  auto fx = [](long long x1, long long x2) -> long long { return min(x1, x2); };
  auto gx = [](long long x1, long long x2) -> long long { return max(x1, x2); };
  long long ex = numeric_limits<long long>::max();
  SegTree<long long> st1(n, fx, 1223372036854775807LL);
  SegTree<long long> st2(n, gx, -1223372036854775807LL);
  vector<long long> vec(n, 0);
  for (long long i = 0; i < n; i++) {
    cin >> vec[i];
  }
  sort((vec).begin(), (vec).end());
  for (long long i = 0; i < n; i++) {
    st1.set(i, vec[i]);
    st2.set(i, vec[i]);
  }
  st1.build();
  st2.build();
  long long res = 0;
  for (long long i = 0; i < n - max(q, k); i++) {
    chmax(res, st2.query(i, q) - st1.query(i, q));
  }
  cout << res << endl;
  return;
}
int32_t main(int32_t argc, const char *argv[]) {
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);
  std::cout << std::fixed;
  std::cout << std::setprecision(11);
  solve();
  return 0;
}
