#include <bits/stdc++.h>
/// kitsune
using namespace std;
#define fi first
#define se second
#define mp make_pair
//#define int long long
#define sz(x) (int)(x).size()
#define all(x) (x).begin(), (x).end()
#define rep(i, l, r) for (int i = (int)(l); i <= (int)(r); i++)
#define per(i, r, l) for (int i = (int)(r); i >= (int)(l); i--)
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
template<typename _Tp> bool minimize(_Tp &__a, const _Tp &__b) { if (__a > __b) { __a = __b; return true; } return false; }
template<typename _Tp> bool maximize(_Tp &__a, const _Tp &__b) { if (__a < __b) { __a = __b; return true; } return false; }
const int siz = 2e3 + 2;
const int SIZ = 1e6 + 2;
const int mod = 1e9 + 7;
const int maxx = 2e9;
const ll MAXX = 1e18;
const string file = "1";
int n, a, b;
int p[siz];
int dp[siz][siz];
bool check(int w) {
memset(dp, 0x3f, sizeof(dp));
dp[0][0] = 0;
rep (i, 1, n) {
int j_1 = lower_bound(p + 1, p + n + 1, p[i] - w + 1) - p - 1;
int j_2 = lower_bound(p + 1, p + n + 1, p[i] - 2 * w + 1) - p - 1;
rep (k, 0, a) {
if (k > 0) {
minimize(dp[i][k], dp[j_1][k - 1]);
}
minimize(dp[i][k], dp[j_2][k] + 1);
}
}
rep (k, 0, a) {
if (dp[n][k] <= b) {
return true;
}
}
return false;
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
// freopen((file + ".inp").c_str(), "r", stdin);
// freopen((file + ".out").c_str(), "w", stdout);
cin >> n >> a >> b;
minimize(a, n);
minimize(b, n);
rep (i, 1, n) {
cin >> p[i];
}
sort(p + 1, p + n + 1);
int ans = -1;
for (int lb = 1, rb = 1e9; lb <= rb; ) {
int mb = (lb + rb) / 2;
if (check(mb)) {
ans = mb;
rb = mb - 1;
} else {
lb = mb + 1;
}
}
cout << ans << "\n";
// cerr << "Time: " << 1000 * clock() / CLOCKS_PER_SEC << " ms\n";
return 0;
}
