#include <bits/stdc++.h>
using namespace std;
const int N = 1 << 11;
int n, P, Q, a[N], dp[N][N];
bool f(int w) {
dp[0][0] = 0;
for (int i = 1; i <= n; ++i) {
int j = i, k = i;
while (j && a[i] - a[j] < w) --j;
while (k && a[i] - a[k] < 2 * w) --k;
dp[i][0] = 1 + dp[k][0];
for (int p = 1; p <= P; ++p) dp[i][p] = min(dp[j][p - 1], 1 + dp[k][p]);
}
for (int p = 0; p <= P; ++p) if (dp[n][p] <= Q) return true;
return false;
}
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> P >> Q;
for (int i = 1; i <= n; ++i) cin >> a[i];
if (n <= P) return cout << 1, 0;
sort(a, a + n);
int l = 0, r = a[n] - a[1] + 1;
while (r - l > 1) {
int m = l + (r - l + 1) / 2;
(f(m) ? r : l) = m;
}
cout << r;
}
