/**
____ ____ ____ ____ ____
||a |||t |||o |||d |||o ||
||__|||__|||__|||__|||__||
|/__\|/__\|/__\|/__\|/__\|
**/
#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int N_MAX = 2000;
int N, P, Q;
int A[N_MAX + 2];
int dp[N_MAX + 2][N_MAX + 2];
bool solve (int w) {
int jp = 0, jq = 0;
for (int i = 1; i <= N; i++) {
while (A[i] - A[jp] + 1 > w) {
jp++;
}
while (A[i] - A[jq] + 1 > w * 2) {
jq++;
}
for (int cntp = 0; cntp <= min(i, P); cntp++) {
/// Use a large camera (Q)
dp[i][cntp] = dp[jq - 1][cntp] + 1;
/// Use a small camera (P)
if (cntp > 0) {
dp[i][cntp] = min(dp[i][cntp], dp[jp - 1][cntp - 1]);
}
}
}
for (int cntp = 0; cntp <= min(N, P); cntp++) {
if (dp[N][cntp] <= Q) {
return true;
}
}
return false;
}
int main () {
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> N >> P >> Q;
for (int i = 1; i <= N; i++) {
cin >> A[i];
}
sort(A + 1, A + N + 1);
int l = 1, r = (int) 1e9;
while (l < r) {
int mid = (l + r) / 2;
if (solve(mid) == true) {
r = mid;
} else {
l = mid + 1;
}
}
cout << l << "\n";
return 0;
}
