#include <bits/stdc++.h>
#define int long long
using namespace std;
int inf = 1e18;
int a[2001];
int dp[2001][2001];
int cook(int w, int n, int p){
for (int i = 0;i<=n;++i){
for (int j = 0;j<=p;++j){
dp[i][j] = inf;
}
}
for (int i = 0;i<=p;++i){
dp[0][i] = 0;
}
vector<int> ps(n+1, 0);
vector<int> pl(n+1, 0);
int l = 1, ll = 1;
for (int i = 1;i<=n;++i){
while(l<i and a[i]-a[l]>=w){
l++;
}
while(ll<i and a[i]-a[ll]>=2*w){
ll++;
}
ps[i] = l;
pl[i] = ll;
}
/*for (int i = 1;i<=n;++i){
cout << ps[i] << ' ';
}
cout << '\n';
for (int i =1;i<=n;++i){
cout << pl[i] << ' ';
}
cout << '\n';*/
for (int i = 1;i<=n;++i){
dp[i][0] = dp[pl[i]-1][0] +1;
for (int j = 1;j<=p;++j){
dp[i][j] = min(dp[ps[i]-1][j-1], dp[pl[i]-1][j]+1);
}
}
return dp[n][p];
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
int n, p, q;
cin >> n >> p >> q;
for (int i = 1;i<=n;++i){
cin >> a[i];
}
sort(a+1, a+n+1);
int l = 1, r = 1000000000;
// int l = 14, r = 14;
int res = 1;
while(l<=r){
int w = (l+r)/2;
int t = cook(w, n, min(n, p));
// cout << w << ' ' << t << '\n';
if(t <= q){
res = w;
r = w-1;
}else l = w+1;
}
cout << res;
}
