#include <bits/stdc++.h>
using namespace std;
int const maxn = 2005;
int a[maxn], b[maxn], inf = 1e9 + 1, n;
inline int ok(int x, int y, int k, int q) {
  int cnt = 0, go = 0, good = 0;
  for (int i = 1; i <= n; ++i) {
    if (a[i] < x) {
      cnt += max(0, min(good, go - k + 1));
      go = 0, good = 0;
    } else {
      go++;
      if (a[i] <= y) good++;
    }
  }
  cnt += max(0, min(good, go - k + 1));
  return cnt >= q;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  int k, q, ans = inf;
  cin >> n >> k >> q;
  for (int i = 1; i <= n; ++i) {
    cin >> a[i];
    b[i] = a[i];
  }
  sort(b + 1, b + n + 1);
  int i = 1, j = 1;
  while (i <= n) {
    while (j <= n && !ok(b[i], b[j], k, q)) ++j;
    if (j <= n) ans = min(ans, b[j] - b[i]);
    ++i;
  }
  cout << ans << '\n';
  return 0;
}
