#include <bits/stdc++.h>
using namespace std;
#define F first
#define S second
#define MP make_pair
#define PB push_back
using ll = long long;
using ld = long double;
using pi = pair<int, int>;
using pll = pair<ll, ll>;
template<typename T>
using vec = vector<T>;
template<typename T, int N>
using arr = array<T, N>;
ll gcd(ll a, ll b) { return b == 0 ? a : gcd(b, a % b); }
ll lcm(ll a, ll b) { return a * b / gcd(a, b); }
const int INF = 1e9 + 7;
int dp[2001][2001];
int main()
{
cin.tie(0) -> sync_with_stdio(0);
int N, P, Q;
cin >> N >> P >> Q;
vec<int> A(N + 1);
for (int i = 1; i <= N; i++)
cin >> A[i];
sort(A.begin() + 1, A.end());
auto f = [&](int w) {
vec<int> U(N + 1), V(N + 1);
for (int i = 1; i <= N; i++)
{
U[i] = upper_bound(A.begin() + 1, A.end(), A[i] - w) - A.begin() - 1;
V[i] = upper_bound(A.begin() + 1, A.end(), A[i] - 2 * w) - A.begin() - 1;
}
for (int i = 1; i <= N; i++)
{
for (int j = 0; j <= min(N, Q); j++)
{
if (j == 0) dp[i][j] = dp[U[i]][j] + 1;
else dp[i][j] = min(dp[U[i]][j] + 1, dp[V[i]][j - 1]);
}
}
return (dp[N][min(N, Q)] <= P);
};
int l = 1, r = 1e9;
while (l <= r)
{
int m = (l + r) / 2;
if (f(m)) r = m - 1;
else l = m + 1;
}
cout << l << '\n';
}
