#include <bits/stdc++.h>
#define GOOD_LUCK ios_base::sync_with_stdio(false); cin.tie(0); cout.tie(0);
// #define int long long
#define endl "\n"
#define ff first
#define ss second
#define pb push_back
#define all(v) v.begin(), v.end()
using namespace std;
constexpr int MAX = 2e+5 + 1, INF = 1e+9, MOD = 1e+9 + 7, K = 31;
void _() {
int n, p, q;
cin >> n >> p >> q;
vector <int> v(n);
for (int &i : v) cin >> i;
if (p + q >= n) {
cout << 1;
return;
}
v.pb(-INF);
sort(all(v));
int l = 1, r = INF, res;
while (l <= r) {
int m = (l + r) / 2;
vector <vector <int>> dp(n+1, vector <int>(p+1, INF));
dp[0][0] = 0;
for (int i = 1; i <= n; i++) {
int x = v[i] - m + 1;
auto it = lower_bound(all(v), x);
--it;
int id1 = it - v.begin();
x = v[i] - 2 * m + 1;
auto it1 = lower_bound(all(v), x);
--it1;
int id2 = it1 - v.begin();
for (int j = 0; j <= p; j++) {
int ans = INF;
if (j) {
ans = min(ans, dp[id1][j-1]);
}
if (id2 != i) ans = min(ans, dp[id2][j] + 1);
dp[i][j] = ans;
}
}
if (*min_element(all(dp[n])) <= q) {
res = m;
r = m - 1;
}
else l = m + 1;
}
cout << res;
}
signed main() {
GOOD_LUCK
int tests=1;
// cin >> tests;
for (int i=1; i <= tests; i++) {
_();
cout << endl;
}
return 0;
}
