#include <bits/stdc++.h>
using namespace std;
#ifdef LOCAL
#include "debug.h"
#else
#define debug(...) 42
#endif
#define int long long
#define fi first
#define se second
const int N = 2001;
int n, a[N], P, Q;
bool check(int d) {
int eff = min(Q, 2000LL);
vector<vector<int>> dp(n+1, vector<int> (eff+1, 1e9));
dp[0][0] = 0;
for (int i = 1; i <= n; i++) {
int lstq = 0, lstp = 0;
for (int j = i - 1; j >= 0; j--) {
lstq = j;
if (a[j] + 2 * d <= a[i]) break;
}
for (int j = i - 1; j >= 0; j--) {
lstp = j;
if (a[j] + d <= a[i]) break;
}
for (int j = 0; j <= eff; j++) {
if (j) dp[i][j] = min(dp[i][j], dp[lstq][j - 1]);
dp[i][j] = min(dp[i][j], dp[lstp][j] + 1);
}
}
// for (int j = 0; j <= eff; j++) debug(dp[n][j]);
for (int j = 0; j <= eff; j++) if (dp[n][j] <= P) return true;
return false;
}
void solve() {
cin >> n >> P >> Q;
a[0] = -1e18;
for (int i = 1; i <= n; i++) cin >> a[i];
sort(a + 1, a + n + 1);
int l = 0, r = 1e9;
while (l < r) {
int mid = (l + r) / 2;
if (check(mid)) r = mid;
else l = mid + 1;
}
cout << l << '\n';
}
int32_t main() {
ios::sync_with_stdio(0); cin.tie(0);
int test = 1;
// cin >> test;
while (test--) solve();
}
