#include <iostream>
#include <bits/stdc++.h>
#define ll long long
using namespace std;
const ll maxn = 2*1e5+5, INF = 1e9+9;
struct normalize{
vector<ll> poi, pot;
void add(ll x){
poi.push_back(x);
}
void start(){
sort(poi.begin(), poi.end());
pot.push_back(poi[0]);
for(int i = 1; i < (int)poi.size(); i++){
if(poi[i] != poi[i-1]){
pot.push_back(poi[i]);
}
}
}
int encode(ll x){
return lower_bound(pot.begin(), pot.end(), x) - pot.begin()+1;
}
};
void solve(){
int n, P, Q;
cin >> n >> P >> Q;
P = min(P, n);
vector<ll> a(n+1);
for(int i = 1; i <= n; i++){
cin >> a[i];
}
sort(a.begin()+1, a.end());
vector<vector<int>> p(n+1, vector<int>(3));
//minimum number of big camera need for prefix-i event, j small camera used
vector<vector<int>> f(n+1, vector<int>(P+1));
auto check = [&](ll x) -> bool{
for(int i = 1; i <= n; i++){
p[i][1] = lower_bound(a.begin()+1, a.end(), a[i]-x+1) - a.begin();
p[i][2] = lower_bound(a.begin()+1, a.end(), a[i]-x*2+1) - a.begin();
}
for(int i = 0; i <= n; i++){
for(int j = 0; j <= P; j++){
f[i][j] = INF;
}
}
f[0][0] = 0;
for(int i = 1; i <= n; i++){
for(int j = 0; j <= P; j++){
if(j > 0) f[i][j] = min(f[i][j], f[p[i][1]-1][j-1]);
f[i][j] = min(f[i][j], f[p[i][2]-1][j]+1);
}
}
int mn = INF;
for(int j = 0; j <= P; j++){
mn = min(mn, f[n][j]);
}
return mn <= Q;
};
ll l = 1, r = 1e9, mid;
while(l <= r){
mid = (l+r)/2;
if(check(mid)){
r = mid-1;
}else{
l = mid+1;
}
}
cout << l;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(NULL);
solve();
}
