#include <bits/stdc++.h>
using namespace std;
const int N = 2005;
int main() {
cin.tie(0)->sync_with_stdio(0);
int n, p, q;
cin >> n >> p >> q;
vector<int> a(n + 1);
for (int i = 1; i <= n; i++) {
cin >> a[i];
}
if (n - p - q <= 0) {
cout << 1 << '\n';
return 0;
}
sort(a.begin() + 1, a.end());
auto check = [&](int m) {
vector<vector<int>> dp(n + 1, vector<int>(p + 1, 1e9));
for (int i = 0; i <= p; i++) {
dp[0][i] = 0;
}
int pp = 1, pq = 1;
for (int i = 1; i <= n; i++) {
while (a[i] - a[pp] + 1 > m) pp++;
while (a[i] - a[pq] + 1 > 2 * m) pq++;
dp[i][0] = dp[pq - 1][0] + 1;
for (int j = 1; j <= p; j++) {
dp[i][j] = min(dp[pq - 1][j] + 1, dp[pp - 1][j - 1]);
}
}
return (dp[n][p] <= q);
};
int l = 1, r = 1e9, ans = -1;
while (l <= r) {
int m = (l + r) / 2;
if (check(m)) {
ans = m;
r = m - 1;
}
else l = m + 1;
}
cout << ans << '\n';
}
