#include <bits/stdc++.h>
using namespace std;
#define fast ios::sync_with_stdio(0);cin.tie(0);
#define s second
#define f first
typedef long long ll;
const ll MOD = 1e9+9;
const ll LOGN = 20;
const ll MAXN = 2005;
vector<int> A;
int dp[MAXN][MAXN], P, N, Q;
bool check(int w) {
for (int i = 0; i < MAXN; i++) {
for (int j = 0; j < MAXN; j++)
dp[i][j] = 1e7;
}
dp[0][0] = 0;
int r_w = 1, r_2w = 1;
while (r_w != N && A[r_w + 1] - A[1] < w)
r_w++;
while (r_2w != N && A[r_2w + 1] - A[1] < 2*w)
r_2w++;
for (int i = 1; i <= N; i++) {
for (int j = 0; j <= P; j++) {
while (r_w != N && A[r_w + 1] - A[i] < w)
r_w++;
while (r_2w != N && A[r_2w + 1] - A[i] < 2*w)
r_2w++;
dp[r_w][j+1] = min(dp[r_w][j+1], dp[i-1][j]);
dp[r_2w][j] = min(dp[r_2w][j], dp[i-1][j] + 1);
}
}
for (int used_w = 0; used_w <= P; used_w++) {
if (dp[N][used_w] <= Q)
return true;
}
return false;
}
int main() {
cin >> N >> P >> Q;
if (P + Q >= N) {
cout << "1\n";
return 0;
}
A = vector<int>(N+1);
A[0] = 0;
for (int i = 1; i <= N; i++)
cin >> A[i];
sort(A.begin(), A.end());
int L = 1;
int R = 1e9;
int ans = -1;
while (R >= L) {
int mid = L + (R-L)/2;
if (check(mid)) {
R = mid - 1;
ans = mid;
} else
L = mid + 1;
}
cout << ans << "\n";
}
