#include <bits/stdc++.h>
using namespace std;
const int N = 2000;
int a[N + 1];
int main() {
  int n, k, q;
  scanf("%d%d%d", &n, &k, &q);
  for (int i = 0; i < n; i++) scanf("%d", &a[i]);
  int ans = 1e9;
  for (int& bound : a) {
    vector<int> t;
    vector<int> s;
    for (int i = 0; i <= n; i++) {
      if (i == n || a[i] < bound) {
        sort(t.begin(), t.end());
        for (int i = 0; i <= (int)t.size() - k; i++) s.push_back(t[i]);
        t.clear();
      } else
        t.push_back(a[i]);
    }
    if ((int)s.size() < q) continue;
    sort(s.begin(), s.end());
    ans = min(ans, s[q - 1] - bound);
  }
  printf("%d\n", ans);
  return 0;
}
