#pragma GCC optimize("O3")
#include <bits/stdc++.h>
using namespace std;
# define int long long
# define QR ios_base::sync_with_stdio(false); cin.tie(nullptr); cout.tie(nullptr);
# define endl '\n'
# define all(x) x.begin(), x.end()
# define ff first
# define ss second
# define pb push_back
const int N = 10001;
const int mod = 1e9;
const int inf = 2e9;
int n, p, q;
int a[N];
bool check(int x)
{
vector<vector<int>> dp(n + 1, vector<int>(p + 1, inf));
vector<int> k(n + 1, 0);
vector<int> b(n + 1, 0);
for (int i = 0; i < n; ++i){
k[i] = upper_bound(a + 1, a + n + 1, a[i + 1] + x - 1) - a - 1;
b[i] = upper_bound(a + 1, a + n + 1, a[i + 1] + 2 * x - 1) - a - 1;
}
dp[0][0] = 0;
for (int i = 0; i < n; ++i)
{
for (int j = 0; j <= p; ++j)
{
if (j < p)
dp[k[i]][j + 1] = min(dp[k[i]][j + 1], dp[i][j]);
dp[b[i]][j] = min(dp[b[i]][j], dp[i][j] + 1);
}
}
int ans = 0;
for (int j = 0; j <= p; ++j)
if (dp[n][j] <= q)
ans = 1;
return ans;
}
void CASE() {
cin >> n >> p >> q;
a[0] = 1;
for (int i = 1; i <= n; ++i)
cin >> a[i];
sort(a + 1, a + n + 1);
if (p + q >= n)
{
cout << 1 << '\n';
return;
}
int l = 1, r = 1e9 ;
int res = 1e9;
while (l <= r){
int mid = l + (r - l) / 2;
if (check(mid)){
res = mid;
r = mid - 1;
}
else
l = mid + 1;
}
cout << res << endl ;
}
signed main() {
QR;
int TESTS = 1;
// cin >> TESTS;
for (int TEST = 1; TEST <= TESTS; TEST++) {
// cout << "Case #TEST << ": " ;
CASE();
}
return 0;
}
