#include <bits/stdc++.h>
using namespace std;
#define print(l) for(auto i:l) cout<<i<<" ";cout<<endl;
#define input(t,l,n) vector<t>l(n);for(int i = 0;i<n;i++)cin>>l[i];
#define int long long
#define pb push_back
#define ordered_set tree<int, null_type,less<int>, rb_tree_tag,tree_order_statistics_node_update>
#define all(l) l.begin(),l.end()
#define pii pair<int,int>
#define fi first
#define se second
const int M = 1e9+7;
const int inf = 1e18;
int bp(int x, int y, int p){
int res = 1;
x = x % p;
while (y > 0) {
if (y & 1)
res = (res * x) % p;
y = y >> 1;
x = (x * x) % p;
}
return res;
}
int MI(int n, int p){
return bp(n, p - 2, p);
}
int mul(int x,int y, int p){
return x * 1ull * y % p;
}
int di(int x,int y, int p){
return mul(x, MI(y, p), p);
}
int n , m , k , q ,p;
void solve(int testcase_number){
cin>>n>>p>>q;
input(int,a,n);
if(p+q >= n){
cout<<1<<endl;
return;
}
sort(all(a));
// print(a);
a.pb(inf);
int l =0 ;
int r = 1e9+10;
while(r-l > 1){
int m = (l+r)/2;
int f = 1;
vector<vector<int>>dp(n+1,vector<int>(p+1,0));
dp[0][0] = 0;
for(int i = 1;i<=n;i++){
int lo = 0;
int hi = 0;
while( a[i-1]-a[lo] >= m ){
lo++;
}
while(a[i-1]-a[hi] >=2*m){
hi++;
}
for(int j = 0;j<=p;j++){
dp[i][j] = dp[hi][j]+1;
if(j != 0){
dp[i][j] = min(dp[i][j],dp[lo][j-1]);
}
}
}
if(dp[n][p] <= q){
r = m;
}
else{
l= m;
}
}
cout<<r<<endl;
}
signed main(){
ios::sync_with_stdio(0);//DO NOT USE IN INTERACTIVE
cin.tie(0), cout.tie(0);
cout << fixed<<setprecision(9);
int t = 1;
// cin>>t;
for(int i = 1;i<=t;i++){
solve(i);
}
}
