#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N = 2e5 + 5;
int n, P, Q, a[N];
bool check(int mid) {
int i = 1;
int p = P, q = Q;
while (i <= n) {
int j = i;
while (j <= n && a[j] - a[i] <= mid - 1) j++;
if (p > 0) {
p--;
i = j;
continue;
}
j = i;
while (j <= n && a[j] - a[i] <= 2 * mid - 1) j++;
if (q > 0) {
q--;
i = j;
continue;
}
return false;
}
return true;
}
signed main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> P >> Q;
for (int i = 1; i <= n; ++i) cin >> a[i];
sort(a + 1, a + n + 1);
int l = 0, r = 1e9, ans = -1;
while (l <= r) {
int mid = (l + r) / 2;
if (check(mid)) {
ans = mid;
r = mid - 1;
} else {
l = mid + 1;
}
}
cout << ans << '\n';
}
