#include<bits/stdc++.h>
using namespace std;
#define int long long
const int N = 2005, inf = 1e18;
int n, p, q, a[N], dp[N][N];
signed main () {
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> p >> q;
if (p >= n || q >= n) return cout << 1, 0;
for (int i = 1; i <= n; ++i) cin >> a[i];
sort (a + 1, a + n + 1);
int l = 1, r = 1000000000;
while (l < r) {
int mid = (l + r) >> 1, pter1, pter2;
pter1 = pter2 = 1;
memset (dp, 63, sizeof dp);
dp[0][0] = 0;
for (int i = 0; i < n; ++i) {
for (int j = 0; j <= p; ++j) {
if (dp[i][j] >= inf) continue;
while (pter1 <= n && a[pter1] <= a[i + 1] + mid - 1) pter1++;
dp[pter1 - 1][j + 1] = min (dp[pter1 - 1][j + 1], dp[i][j]);
while (pter2 <= n && a[pter2] <= a[i + 1] + 2 * mid - 1) pter2++;
dp[pter2 - 1][j] = min (dp[pter2 - 1][j], dp[i][j] + 1);
}
}
bool ok = 0;
for (int j = 0; j <= p; ++j) {
if (dp[n][j] <= q) { ok = 1; break; }
}
if (ok) r = mid;
else l = mid + 1;
}
cout << l;
return 0;
}
