#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 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)
{
int p = P, q = Q;
for (int i = 1; i <= N; )
{
if (i > N) break;
else if (p && !q || p && lower_bound(A.begin() + 1, A.end(), A[i] + w) == lower_bound(A.begin() + 1, A.end(), A[i] + 2 * w))
{
p--;
i = lower_bound(A.begin() + 1, A.end(), A[i] + w) - A.begin();
}
else if (q)
{
q--;
i = lower_bound(A.begin() + 1, A.end(), A[i] + 2 * w) - A.begin();
}
else if (i <= N)
return 0;
}
return 1;
};
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';
}
