#include <bits/stdc++.h>
// #include <ext/rope>
// #include <ext/pb_ds/assoc_container.hpp>
// using namespace __gnu_pbds;
// using namespace __gnu_cxx;
using namespace std;
// #define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define ll long long
#define ull unsigned long long
#define ld long double
#define pb push_back
#define bit(mask, i) ((mask >> i) & 1)
#define el '\n'
#define F first
#define S second
template <class X, class Y> bool maximize(X &x, const Y &y) { return (x < y ? x = y, 1 : 0); }
template <class X, class Y> bool minimize(X &x, const Y &y) { return (x > y ? x = y, 1 : 0); }
const int INF = 1e9;
const ll LINF = 1e18;
const int MOD = 1e9 + 7;
const int MULTI = 0;
const ld eps = 1e-9;
const int dx[4] = {0, 1, 0, -1}, dy[4] = {1, 0, -1, 0}; // R D L U
const int ddx[4] = {-1, 1, 1, -1}, ddy[4] = {1, 1, -1, -1}; // UR DR DL UL
const char cx[4] = {'R', 'D', 'L', 'U'};
const ll base = 31;
const int nMOD = 2;
const ll mods[] = {(ll)1e9 + 10777, (ll)1e9 + 19777, (ll)1e9 + 3, (ll)1e9 + 3777};
const int N = 2e3 + 5;
int n, p, q, a[N], limS[N], limL[N], dp[N][N];
bool check(int w) {
memset(dp, 0x3f, sizeof(dp));
for (int i = 1; i <= n; ++i) {
limS[i] = limL[i] = i;
int l = 1, r = i - 1;
while (l <= r) {
int mid = (l + r) >> 1;
if (a[i] - a[mid] + 1 <= w) {
limS[i] = mid;
r = mid - 1;
} else l = mid + 1;
}
l = 1, r = i - 1;
while (l <= r) {
int mid = (l + r) >> 1;
if (a[i] - a[mid] + 1 <= 2 * w) {
limL[i] = mid;
r = mid - 1;
} else l = mid + 1;
}
}
dp[0][0] = 0;
for (int i = 1; i <= n; ++i)
for (int j = 0; j <= min(p, i); ++j) {
if (j > 0 && dp[limS[i] - 1][j - 1] < INF) minimize(dp[i][j], dp[limS[i] - 1][j - 1]);
if (dp[limL[i] - 1][j] < INF) minimize(dp[i][j], dp[limL[i] - 1][j] + 1);
}
for (int j = 1; j <= p; ++j)
if (dp[n][j] <= q)
return 1;
return 0;
}
void solve() {
cin >> n >> p >> q;
for (int i = 1; i <= n; ++i)
cin >> a[i];
minimize(p, n);
minimize(q, n);
sort(a + 1, a + 1 + n);
int L = 1, R = INF, res = -1;
while (L <= R) {
int mid = (L + R) >> 1;
if (check(mid)) {
res = mid;
R = mid - 1;
} else L = mid + 1;
}
cout << res;
}
signed main() {
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
if (!MULTI) solve();
else {
int test; cin >> test;
while (test--) solve();
}
return 0;
}
