#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, a, b) for(ll i=ll(a); i<ll(b); i++)
#define repn(i, a, b) for(ll i=ll(b)-1; i>=ll(a); i--)
#define pb push_back
#define si size()
#define ff first
#define ss second
#define be begin()
#define en end()
const ll N=2002, P=2002;
vector<vector<ll>> dp(N, vector<ll> (P, N));
bool check(ll n, ll p, ll q, ll w, vector<ll> &v){
dp[0][0]=1;
rep(i, 1, p+1){
dp[0][i]=0;
}
ll c=0;
rep(i, 1, n){
if(v[c]+2*w-1>=v[i]){
dp[i][0]=dp[i-1][0];
}
else{
c=i;
dp[i][0]=dp[i-1][0]+1;
}
}
rep(i, 1, n){
rep(j, 1, p+1){
dp[i][j]=N;
if(v[0]+w>v[i]){
dp[i][j]=0;
}
else{
ll lo=0, hi=i-1;
while(lo<hi){
ll mid=(lo+hi+1)/2;
if(v[mid]+w<=v[i]){
lo=mid;
}
else{
hi=mid-1;
}
}
dp[i][j]=min(dp[i][j], dp[lo][j-1]);
}
if(v[0]+2*w>v[i]){
dp[i][j]=min(dp[i][j], ll(1));
}
else{
ll lo=0, hi=i-1;
while(lo<hi){
ll mid=(lo+hi+1)/2;
if(v[mid]+2*w<=v[i]){
lo=mid;
}
else{
hi=mid-1;
}
}
dp[i][j]=min(dp[i][j], dp[lo][j]+1);
}
}
}
if(dp[n-1][p]<=q){
return true;
}
return false;
}
void solve(){
ll n, p, q;
cin>>n>>p>>q;
vector<ll> v(n);
rep(i, 0, n){
cin>>v[i];
}
sort(v.be, v.en);
if(p+q>=n){
cout<<1;
}
else{
ll lo=1, hi=(1e9)/3+2;
while(lo<hi){
ll mid=(lo+hi)/2;
bool f=check(n, p, q, mid, v);
if(f) hi=mid;
else lo=mid+1;
}
cout<<hi;
}
}
int main(){
ios_base::sync_with_stdio();
cin.tie(0);
ll t=1;
//~ cin>>t;
while(t--){
solve();
}
return 0;
}
