//Oh? You're Approaching Me?
#include <bits/stdc++.h>
using namespace std;
#define int long long
typedef long long ll;
typedef pair<ll, ll> pll;
typedef pair<int, int> pii;
//#pragma GCC optimize("O3,unroll-loops")
#define migmig ios::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define pb push_back
#define F first
#define S second
#define SZ(x) ll((x).size())
#define all(x) (x).begin(), (x).end()
#define cl clear
#define endl '\n'
#define deb(x) cerr << #x << " = " << x << '\n'
#define dokme(x) {cout << x << endl; return;}
#define wtf cout << "[ahaaaaaaaaaaaaaaaa]" << endl;
const int maxn = 3000 + 10;
const int mod = 1e9 + 7; //998244353
const int inf = 1e9 + 5;
const int LOG = 24;
//g++ main.cpp -o main && main.exe
int n, p, q, a[maxn], l1[maxn], l2[maxn], dp[maxn][maxn];
bool check(int x) {
for (int i = 1; i <= n; i++) {
l1[i] = upper_bound(a + 1, a + n + 1, a[i] - x) - a;
l2[i] = upper_bound(a + 1, a + n + 1, a[i] - 2 * x) - a;
// deb(i);
// cout << l1[i] << ' ' << l2[i] << '\n';
}
dp[0][0] = 0;
for (int i = 1; i <= n; i++) {
dp[i][0] = dp[l2[i] - 1][0] + 1;
for (int j = 1; j <= p; j++) {
dp[i][j] = dp[i][j - 1];
dp[i][j] = min(dp[i][j], dp[l1[i] - 1][j - 1]);
dp[i][j] = min(dp[i][j], dp[l2[i] - 1][j] + 1);
}
}
// deb(dp[2][1]);
return (dp[n][p] <= q);
}
signed main() {
cin >> n >> p >> q;
for (int i = 1; i <= n; i++)
cin >> a[i];
sort(a + 1, a + n + 1);
if (p >= n || q >= n) {
cout << 1 << '\n';
return 0;
}
int l = 0, r = 2 * inf;
while (r - l > 1) {
int mid = (l + r) / 2;
if (check(mid))
r = mid;
else
l = mid;
}
cout << r << '\n';
// cout << check(3) << '\n';
// deb(dp[3][1]);
// deb(l2[3]);
}
// 3 1 1
// 2
// 11
// 17
