#include <bits/stdc++.h>
// #include <ext/pb_ds/assoc_container.hpp>
using namespace std;
// using namespace __gnu_pbds;
// template <typename T>
// using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#define int long long
#define pb push_back
#define eb emplace_back
#define pf push_front
#define ppb pop_back
#define ppf pop_front
#define ins insert
#define ff first
#define ss second
// mt19937_64 rng(chrono::steady_clock::now().time_since_epoch().count());
constexpr int inf = 1e9+10, mod = 1e9+7, maxn = 300005;
int n, p, q;
vector<int> a;
bool ok(int w){
vector<vector<int>> dp(n+1, vector<int>(q+1, inf));
for (int cnt = 0; cnt <= q; cnt++){
dp[0][cnt] = 0;
}
int l1 = 1, l2 = 1;
for (int i = 1; i <= n; i++){
while (l1 <= i && a[i]-a[l1]+1 > w+w){
l1++;
}
while (l2 <= i && a[i]-a[l2]+1 > w){
l2++;
}
for (int cnt = 0; cnt <= q; cnt++){
dp[i][cnt] = min(dp[i][cnt], dp[l2 - 1][cnt] + 1);
if (cnt > 0) {
dp[i][cnt] = min(dp[i][cnt], dp[l1 - 1][cnt - 1]);
}
}
}
for (int cnt = 0; cnt <= q; cnt++){
if (dp[n][cnt] <= p){
return true;
}
}
return false;
}
void solve(){
cin >> n >> p >> q;
a.assign(n+1, 0);
for (int i = 1; i <= n; i++){
cin >> a[i];
}
sort(a.begin(), a.end());
int l = 0, r = 1e10, m;
while (r-l>1){
m = l+(r-l)/2;
if (ok(m)){
r = m;
} else{
l = m;
}
}
cout << r << '\n';
}
signed main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
int t = 1;
// cin >> t;
for (int i = 0; i < t; i++) {
solve();
}
return 0;
}
