#include <iostream>
#include <vector>
#include <set>
#include <algorithm>
using namespace std;
typedef pair<int, int> P;
#define rep(i, n) for (int i=0; i<(n); i++)
#define all(x) x.begin(), x.end()
#define index(a, b, y) (int)(lower_bound(a, b, y) - a)
#define INF 1000001919
inline void chmin(int &x, int v) { if (x > v) x = v; }
int N, A, B;
int X[2000];
int Fsmall[2000], Flarge[2000];
int dp[2001][2001];
bool f(int W) {
rep(i, N) {
Fsmall[i] = index(X, X+N, X[i]+W);
Flarge[i] = index(X, X+N, X[i]+2*W);
}
rep(i, N+1) rep(j, A+1) dp[i][j] = INF;
dp[0][0] = 0;
rep(i, N) {
rep(j, A+1) {
if (dp[i][j] == INF) continue;
if (j < A) chmin(dp[Fsmall[i]][j+1], dp[i][j]);
if (dp[i][j] < B) chmin(dp[Flarge[i]][j], dp[i][j]+1);
}
}
int m = INF;
rep(i, A+1) chmin(m, dp[N][i]);
return m <= B;
}
int main() {
cin >> N >> A >> B;
rep(i, N) cin >> X[i];
sort(X, X+N);
if (A+B >= N) {
cout << 1 << "\n";
return 0;
}
int lo = 0, hi = INF;
while (hi-lo > 1) {
int mid = (lo+hi)/2;
if (f(mid)) hi = mid;
else lo = mid;
}
cout << hi << "\n";
return 0;
}
