#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
typedef long double ld;
const int MAX_N = 2 * 1e3;
int a[MAX_N + 1];
int dp[MAX_N + 1][MAX_N + 1];
int n, p, q;
bool check(int guess) {
memset(dp, 0, sizeof(dp));
int j = 1, k = 1;
for (int i = 1; i <= n; i++) {
while (a[i] - a[j] >= guess) {
j++;
}
while (a[i] - a[k] >= 2 * guess) {
k++;
}
for (int l = 0; l <= min(i, p); l++) {
dp[i][l] = dp[k - 1][l] + 1;
if (l != 0) {
dp[i][l] = min(dp[i][l], dp[j - 1][l - 1]);
}
}
}
return (dp[n][min(n, p)] <= q);
}
int cb() {
int l = 1, r = 1e9, sol = -1;
while (l <= r) {
int mid = (l + r) / 2;
if (check(mid)) {
sol = mid;
r = mid - 1;
} else {
l = mid + 1;
}
}
return sol;
}
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 ans = cb();
cout << ans;
return 0;
}
