#include <bits/stdc++.h>
// Author: Kazuki_Will_Win_VOI_8703
#define fi first
#define se second
#define pii pair<int, int>
#define int long long
#define all(a) a.begin(), a.end()
using namespace std;
const int mn = 2e3 + 5, bm = (1 << 11) + 1, mod = 1e9 + 7, offset = 5e4, B = 320 + 5;
const int inf = 1e18, base = 311;
int n, p, q, a[mn], dp[mn][mn], pre[2][mn];
bool check(int mid){
for(int i = 1; i <= n; i++){
for(int j = i - 1; j >= 0; j --){
if(a[i] - a[j] >= mid || j == 0){
pre[0][i] = j;
break;
}
}
}
for(int i = 1; i <= n; i++){
for(int j = i - 1; j >= 0; j --){
if(a[i] - a[j] >= 2 * mid || j == 0){
pre[1][i] = j;
break;
}
}
}
fill(&dp[0][0], &dp[0][0] + mn * mn, inf);
dp[0][0] = 0;
for(int i = 1; i <= n; i++){
for(int j = 0; j <= q; j++){
dp[i][j] = min(dp[i][j], dp[pre[0][i]][j] + 1);
if(j > 0) dp[i][j] = min(dp[pre[1][i]][j - 1], dp[i][j]);
}
}
if(dp[n][q] <= p) return true;
return false;
}
void solve(){
cin >> n >> p >> q;
for(int i = 1; i <= n; i++) cin >> a[i];
sort(a + 1, a + n + 1);
int l = 1, r = 1e9, ans = -1;
while(l <= r){
int mid = (l + r) >> 1;
if(check(mid)){
ans = mid;
r = mid - 1;
}
else l = mid + 1;
}
cout << ans << '\n';
}
signed main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
int t = 1;
// cin >> t;
while(t--){
solve();
}
}
