#include <bits/stdc++.h>
#define ll long long
#define all(x) x.begin(), x.end()
#define pb push_back
using namespace std;
const ll inf = 1e10;
bool ok(ll w, vector<ll> &a, ll p, ll q){
ll n = a.size(); p = min(p, n);
vector<vector<ll>>dp(n + 1, vector<ll>(p + 1, inf));
vector<array<ll, 2>>nx(n); dp[0][0] = 0;
for(ll i = 0; i < n; i++){
nx[i][0] = lower_bound(all(a), a[i] + w) - a.begin();
nx[i][1] = lower_bound(all(a), a[i] + 2 * w) - a.begin();
}
for(ll i = 0; i < n; i++){
for(ll j = 0; j <= p; j++){
if(dp[i][j] == inf) continue;
if(j < p) dp[nx[i][0]][j + 1] =
min(dp[nx[i][0]][j + 1], dp[i][j]);
dp[nx[i][1]][j] = min(dp[i][j] + 1, dp[nx[i][1]][j]);
}
}
for(ll i = 0; i <= p; i++){
if(dp[n][i] <= q) return 1;
}
return 0;
}
void sl(){
ll n, p, q; cin >> n >> p >> q;
vector<ll>a(n); for(ll &i : a) cin >> i;
ll l = 0, r = inf, best = inf;
sort(all(a)); while(l <= r){
ll mid = (l + r) / 2;
if(ok(mid, a, p, q)) best = mid, r = mid - 1;
else l = mid + 1;
}
cout << best << endl;
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0); cout.tie(0);
ll t = 1; //cin >> t;
while(t--) sl();
}
