#include <bits/stdc++.h>
using namespace std;
const int INF = 1e9;
int main(){
ios::sync_with_stdio(false);
cin.tie(nullptr);
int N;
int P, Q;
cin >> N >> P >> Q;
vector<long long> A(N);
for (int i = 0; i < N; ++i) cin >> A[i];
sort(A.begin(), A.end());
auto can = [&](long long w)->bool{
vector<int> r1(N), r2(N);
int p1 = 0, p2 = 0;
for (int i = 0; i < N; ++i){
if (p1 < i) p1 = i;
while (p1+1 < N && A[p1+1] <= A[i] + w - 1) ++p1;
r1[i] = p1;
if (p2 < i) p2 = i;
while (p2+1 < N && A[p2+1] <= A[i] + 2*w - 1) ++p2;
r2[i] = p2;
}
int maxSmall = min(P, N);
vector< vector<int> > dp(N+1, vector<int>(maxSmall+1, INF));
dp[0][0] = 0;
for (int i = 0; i < N; ++i){
for (int used = 0; used <= maxSmall; ++used){
int curLarge = dp[i][used];
if (curLarge == INF) continue;
// use small if possible
if (used < maxSmall){
int to = r1[i] + 1;
if (dp[to][used+1] > curLarge) dp[to][used+1] = curLarge;
}
int to2 = r2[i] + 1;
if (dp[to2][used] > curLarge + 1) dp[to2][used] = curLarge + 1;
}
}
for (int used = 0; used <= maxSmall; ++used){
if (dp[N][used] <= Q) return true;
}
return false;
};
long long lo = 1, hi = 1000000000LL, ans = hi;
while (lo <= hi){
long long mid = (lo + hi) >> 1;
if (can(mid)){
ans = mid;
hi = mid - 1;
} else lo = mid + 1;
}
cout << ans << "\n";
return 0;
}
