#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<vi> vvi;
typedef vector<vll> vvll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
typedef vector<pii> vpii;
typedef vector<pll> vpll;
typedef vector<vpii> vvpii;
typedef vector<vpll> vvpll;
#define pb push_back
#define mp make_pair
#define all(x) (x).begin(), (x).end()
#define rall(x) (x).rbegin(), (x).rend()
#define sz(x) (int)(x).size()
#define fi first
#define se second
template<class T> bool ckmin(T &a, const T &b) {return a > b ? a = b, 1 : 0;}
template<class T> bool ckmax(T &a, const T &b) {return a < b ? a = b, 1 : 0;}
namespace debug {
void __print(int x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}
template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ','; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for(auto z : x) cerr << (f++ ? "," : ""), __print(z); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if(sizeof...(v)) cerr << ", "; _print(v...);}
#ifdef DEBUG
#define dbg(x...) cerr << "\e[91m" << "LINE(" << __LINE__ << ") -> " << "[" << #x << "] = ["; _print(x); cerr << "\033[0m";
#else
#define dbg(x...)
#endif
}
using namespace debug;
const char nl = '\n';
mt19937 rng(chrono::high_resolution_clock::now().time_since_epoch().count());
void solve() {
int n, p, q;
cin >> n >> p >> q;
vll v(n);
for(auto &z : v) cin >> z;
sort(all(v));
if(n <= p + q) {
cout << 1 << nl;
return;
}
const int INF = 1e9 + 12;
auto calc = [&](ll x) {
vector<vector<bool>> dp(n + 1, vector<bool>(p + 1, false));
vvi mini(n + 1, vi(p + 1, INF));
dp[0][0] = true;
mini[0][0] = 0;
for(int i = 0; i < n; ++i) {
for(int j = 0; j <= p; ++j) {
if(!dp[i][j]) continue;
if(j + 1 <= p) {
int gde = lower_bound(all(v), v[i] + x) - v.begin();
dp[gde][j + 1] = true;
ckmin(mini[gde][j + 1], mini[i][j]);
}
{
int gde = lower_bound(all(v), v[i] + 2 * x) - v.begin();
dp[gde][j] = true;
ckmin(mini[gde][j], mini[i][j] + 1);
}
}
}
for(int i = 0; i <= p; ++i) {
if(!dp[n][i]) continue;
if(mini[n][i] <= q) return true;
}
return false;
};
ll l = 1, r = 1e9 + 12;
ll ans = -1;
while(l <= r) {
ll mid = l + (r - l) / 2;
if(calc(mid)) {
ans = mid;
r = mid - 1;
} else {
l = mid + 1;
}
}
cout << ans << nl;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int testCases = 1;
//cin >> testCases;
while(testCases--)
solve();
}
