// author : daohuyenchi
#ifdef LOCAL
#include "D:\C++ Submit\debug.h"
#else
#define debug(...)
#endif
#include <bits/stdc++.h>
using namespace std;
#define ull unsigned long long
#define db double
#define i32 int32_t
#define i64 int64_t
#define ll long long
//
#define fi first
#define se second
// #define int long long // consider carefully
//
#define pii pair<int, int>
#define pli pair<ll, int>
#define pll pair<ll, ll>
#define pil pair<int, ll>
#define PAIR make_pair
// TIME IS LIMITED ...
#define rep(i, a, b) for (int i = (a), _b = (b); i <= _b; ++i)
#define repd(i, b, a) for (int i = (b), _a = (a); i >= _a; --i)
#define repv(v, H) for(auto &v: H)
// REFLECT ON THE PAST ...
#define RESET(c, x) memset(c, x, sizeof(c))
#define MASK(i) (1LL << (i))
#define BIT(mask, i) (((mask) >> (i)) & 1LL)
#define ONBIT(mask, i) ((mask) | (1LL << (i)))
#define OFFBIT(mask, i) ((mask) &~ (1LL << (i)))
#define COUNTBIT __builtin_popcountll
// 30 / 1 / 2024 ? love is zero... start from zero
#define vi vector <int>
#define vll vector <ll>
#define lwb lower_bound
#define upb upper_bound
#define all(v) (v).begin(), (v).end()
#define special(H) (H).resize(distance(H.begin(), unique(all(H))))
//
#define sp ' '
#define nl '\n'
#define EL {cerr << '\n';}
#define yes "YES"
#define no "NO"
#define Log2(n) (63 - __builtin_clzll(n))
#define left __left__
#define right __right__
#define lps(id) ((id) << 1)
#define rps(id) ((id) << 1 | 1)
//____________________________________________________________________
template <class X, class Y> bool maximize(X &a, const Y &b) {
if(a < b) return a = b, true;
return false;
}
template <class X, class Y> bool minimize(X &a, const Y &b) {
if(a > b) return a = b, true;
return false;
}
template <class... T>
void print(T&&... n) {
using exp = int[];
exp{0, (cerr << n << sp, 0)...};
cerr << nl;
}
template <class T, class... C>
void assign(int n, T v, C&&... a) {
using e = int[];
e{(a.assign(n, v), 0)...};
}
template <class... C>
void resize(int n, C&&... a) {
using e = int[];
e{(a.resize(n), 0)...};
}
template <class T>
using vector2d = vector<vector<T>>;
template <class T>
using vector3d = vector<vector2d<T>>;
template <class T> int ssize(T &a) { return (int) a.size(); }
//____________________________________________________________________
mt19937 rng(chrono::steady_clock().now().time_since_epoch().count());
const int MOD = 1000000007;
// const int MOD[2] = {1000000009, 998244353};
template<class X> void modmize(X &x, int cur_Mod = MOD) {
if(x >= cur_Mod) x -= cur_Mod;
if(x < 0) x += cur_Mod;
}
const long long oo = 1e18 + 7;
const long long LINF = 1e18 + 7;
const int IINF = 2e9;
const int nmax = 2e3 + 10;
const int MAX = 2e5;
const int base = 311;
const db eps = 1e-6;
const int block = 500;
static const double PI = acos(-1.0);
//____________________________________________________________________
int n, P, Q;
int a[nmax];
int dp[nmax][nmax];
bool bin_check(int val) {
vector2d <int> nxt(n + 2, vector <int>(2, 0));
rep (i, 1, n) {
repd (j, n, i) {
if (a[j] - a[i] + 1 <= val && nxt[i][0] == 0) {
nxt[i][0] = j;
}
if (a[j] - a[i] + 1 <= val * 2 && nxt[i][1] == 0) {
nxt[i][1] = j;
}
}
}
rep (i, 0, n) rep (i2, 0, n) dp[i][i2] = 0;
dp[1][0] = nxt[1][0];
dp[0][1] = nxt[1][1];
rep (i, 0, min(n, P)) {
rep (j, 0, min(n, Q)) {
if (dp[i][j] != 0 && dp[i][j] < n) {
int cur = dp[i][j];
maximize(dp[i + 1][j], max(cur, nxt[cur + 1][0]));
maximize(dp[i][j + 1], max(cur, nxt[cur + 1][1]));
}
}
}
rep (i, 0, min(n, P)) rep (j, 0, min(n, Q)) {
if (dp[i][j] == n) return 1;
}
return 0;
}
void tintingyn() {
cin >> n >> P >> Q;
rep (i, 1, n) {
cin >> a[i];
}
sort(a + 1, a + n + 1);
int l = 1, r = 1e9;
int res = -1;
while (l <= r) {
int mid = (l + r) / 2;
if (bin_check(mid)) {
res = mid;
r = mid - 1;
}
else l = mid + 1;
}
cout << res << nl;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
//________________________________________________________________
#define TASK "3"
if(fopen(TASK".inp", "r")) {
freopen(TASK".inp", "r", stdin);
freopen(TASK".out", "w", stdout);
}
//________________________________________________________________
// CODE FROM HERE ...!
int num_test = 1;
// cin >> num_test;
while(num_test--) {
tintingyn();
}
cerr << '\n' << "Time elapsed: " << (1.0 * clock() / CLOCKS_PER_SEC) << " s\n" << nl;
return 0;
}
