#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize ("O2")
#pragma GCC optimize ("unroll-loops")
#define ll long long
#define pii pair<ll,ll>
#define fi first
#define sec second
#define ld long double
template <typename T>
ostream& operator << (ostream& os, vector<T>tmp){
os << "[";
for(auto x : tmp) os << " " << x;
os << " ]";
return os;
}
template <typename T>
ostream& operator << (ostream& os, set<T>tmp){
os << "[";
for(auto x : tmp) os << " " << x;
os << " ]";
return os;
}
template <typename T>
ostream& operator << (ostream& os, multiset<T>tmp){
os << "[";
for(auto x : tmp) os << " " << x;
os << " ]";
return os;
}
ostream& operator << (ostream& os, pii x){
os << "[";
os << " " << x.fi << " " << x.sec;
os << " ]";
return os;
}
const ll MOD = 998244353;
const ll N = 2e5 + 5;
const ll INF = 2e18;
// modulo operations
void add(ll &a, ll b) { a = (a + b) % MOD; }
void sub(ll &a, ll b) { a -= b; while(a < 0) a += MOD; a %= MOD; }
void mul(ll &a, ll b) { a = (a * b) % MOD; }
ll expo(ll a, ll b) {
ll ans = 1;
while(b > 0){
if(b & 1) mul(ans, a);
mul(a, a);
b /= 2;
}
return ans;
}
int32_t main(){
ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int tc = 1;
// cin >> tc;
for(;tc--;){
ll n, p, q; cin >> n >> p >> q;
vector<ll> a(n + 5);
for(int i = 1; i <= n; i++) cin >> a[i];
sort(a.begin() + 1, a.begin() + 1 + n);
ll l = 1, r = 1e9, ans = -1;
for(;l <= r;){
ll mid = (l + r) / 2;
vector<vector<ll>> dp(n + 5, vector<ll>(p + 5, INF));
vector<ll> l1(n + 5), l2(n + 5);
ll pt = 1, pt2 = 1;
for(int i = 1; i <= n; i++){
while(pt <= n && a[i] - a[pt] + 1 > mid) pt++;
while(pt2 <= n && a[i] - a[pt2] + 1 > 2 * mid) pt2++;
l1[i] = pt, l2[i] = pt2;
}
dp[0][0] = 0;
for(int i = 1; i <= n; i++){
for(int j = 0; j <= p; j++){
dp[i][j] = dp[l2[i] - 1][j] + 1;
if(j) dp[i][j] = min(dp[i][j], dp[l1[i] - 1][j - 1]);
}
}
if(dp[n][p] <= q){
ans = mid;
r = mid - 1;
}
else l = mid + 1;
}
cout << ans << "\n";
}
}
/*
*/
