#include <iostream>
#include <algorithm>
#include <string>
#include <map>
#include <set>
#include <vector>
#include <tuple>
#define endl "\n"
#define int long long int
#define ld long double
#define mp make_pair
#define pb push_back
#define Bound 1e9 + 5
using namespace std;
int n, p, q;
vector<int> arr;
bool cam(int mid) {
vector<vector<int>> dp(n + 5, vector<int>(n + 5, Bound));
for (int i = 0; i <= n; i++) dp[0][i] = 0;
for (int i = 1; i <= n; i++) {
int id1 = lower_bound(arr.begin(), arr.end(), arr[i - 1] - mid + 1) - arr.begin();
int id2 = lower_bound(arr.begin(), arr.end(), arr[i - 1] - 2 * mid + 1) - arr.begin();
for (int j = 0; j <= n; j++) {
if (j != 0) dp[i][j] = min(dp[i][j], dp[id1][j - 1]);
dp[i][j] = min(dp[i][j], dp[id2][j] + 1);
}
}
bool doit = false;
for (int i = 0; i <= n; i++) {
if (i <= p && dp[n][i] <= q) doit = true;
}
return doit;
}
int32_t main()
{
cin >> n >> p >> q;
for (int i = 1; i <= n; i++) {
int a;
cin >> a;
arr.pb(a);
}
sort(arr.begin(), arr.end());
int l = 1, r = Bound, w = 1;
while (l <= r) {
int mid = (l + r) / 2;
if (cam(mid)) r = mid - 1, w = mid;
else l = mid + 1;
}
cout << w << endl;
return 0;
}
