#include <bits/stdc++.h>
#define ll int
#define ld double
#define pb push_back
#define pf push_front
#define ins insert
#define fr first
#define sc second
#define endl "\n"
#define ar array
#define all(x) x.begin(), x.end()
#define rall(x) x.rbegin(), x.rend()
using namespace std;
void start(){ios_base::sync_with_stdio(NULL);cin.tie(nullptr);cout.tie(nullptr);}
const ll inf = 1e9;
const ll mod = 1e9 + 7;
const ll N = 1e5 + 8;
void solve() {
ll i, j;
ll n, p, q;
cin>>n>>p>>q;
vector<ll> a(n);
for(i=0;i<n;i++) cin>>a[i];
sort(all(a));
ll dp[n + 1][p + 1];
if(p + q >= n) {
cout<<1<<endl;
return;
}
ll l = 0, r = (a[n - 1] - a[0] + 3) / 3;
ll low, mn, m;
while(l + 1 < r){
m = (l + r) / 2;
memset(dp, 0x3f, sizeof(dp));
dp[0][0] = 0;
for(i=0;i<n;i++){
for(j=0;j<=p;j++){
if(dp[i][j] > q) continue;
if(j < p){
low = lower_bound(all(a), a[i] + m) - a.begin();
dp[low][j + 1] = min(dp[low][j + 1], dp[i][j]);
}
if(dp[i][j] < q){
low = lower_bound(all(a), a[i] + m * 2) - a.begin();
dp[low][j] = min(dp[low][j], dp[i][j] + 1);
}
}
}
mn = inf;
for(i=0;i<=p;i++) mn = min(mn, dp[n][i]);
if(mn <= q) r = m;
else l = m;
}
cout<<r<<endl;
}
signed main(){
start();
ll t = 1;
//cin>>t;
while(t--) solve();
}
/*
*/
