#include <bits/stdc++.h>
using namespace std;
#define POPCOUNT(n) (__builtin_popcountll((n)))
#define CLZ(n) (__builtin_clzll((n)))
#define CTZ(n) (__builtin_ctzll((n)))
#define LOG(n) (63 - __builtin_clzll((n)))
#define BIT(n, i) (((n) >> (i)) & 1ll)
#define MASK(i) (1ll << (i))
#define FLIP(n, i) ((n) ^ (1ll << (i)))
#define ON(n, i) ((n) | MASK(i))
#define OFF(n, i) ((n) & ~MASK(i))
#define Int __int128
#define fi first
#define se second
typedef long long ll;
typedef unsigned long long ull;
typedef long double ld;
typedef pair<int, int> pii;
typedef pair<long long, long long> pll;
typedef pair<long long, int> pli;
typedef pair<int, long long> pil;
typedef vector<pair<int, int>> vii;
typedef vector<pair<long long, long long>> vll;
typedef vector<pair<long long, int>> vli;
typedef vector<pair<int, long long>> vil;
template <class T1, class T2> bool maximize(T1 &x, T2 y) {
if (x < y) {
x = y;
return true;
}
return false;
}
template <class T1, class T2> bool minimize(T1 &x, T2 y) {
if (x > y) {
x = y;
return true;
}
return false;
}
template <class T> void remove_duplicate(vector<T> &ve) {
sort (ve.begin(), ve.end());
ve.resize(unique(ve.begin(), ve.end()) - ve.begin());
}
mt19937_64 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
long long random(long long l, long long r) {
return uniform_int_distribution<long long>(l, r)(rng);
}
unsigned long long random(unsigned long long l, unsigned long long r) {
return uniform_int_distribution<unsigned long long>(l, r)(rng);
}
template <class T> T random(T r) {
return rng() % r;
}
const int N = 2000 + 5;
const int MOD = 1e9 + 7;
const int inf = 1e9;
const long long INF = 1e18;
int n, P, Q;
int a[N], dp[N][N], preBaby[N], preGiant[N];
bool check(int w) {
for (int i = 1, j = 0, k = 0; i <= n; ++i) {
while (j + 1 < i && a[j + 1] <= a[i] - w) ++j;
while (k + 1 < i && a[k + 1] <= a[i] - 2 * w) ++k;
preBaby[i] = j, preGiant[i] = k;
}
memset(dp, 0x3f, sizeof dp);
// for (int q = 0; q <= Q; ++q) dp[0][q] = 0;
dp[0][0] = 0;
for (int i = 1; i <= n; ++i) {
for (int q = 0; q <= Q; ++q) {
// Take a giant step
if (q > 0) minimize(dp[i][q], dp[preGiant[i]][q - 1]);
// Take a baby step
minimize(dp[i][q], dp[preBaby[i]][q] + 1);
}
}
for (int q = 0; q <= Q; ++q) if (dp[n][q] <= P) {
return true;
}
return false;
}
signed main() {
ios_base::sync_with_stdio(false); cin.tie(NULL); cout.tie(NULL);
cin >> n >> P >> Q;
for (int i = 1; i <= n; ++i) cin >> a[i];
if (P + Q >= n) return cout << "1", 0;
sort (a + 1, a + 1 + n);
int low = 1, high = inf, ans = -1;
while (low <= high) {
int mid = (low + high) >> 1;
if (check(mid)) high = (ans = mid) - 1;
else low = mid + 1;
}
cout << ans;
return 0;
}
