#include <bits/stdc++.h>
using namespace std;
#define int long long
#define inf LLONG_MAX/20
#define fastio() ios_base::sync_with_stdio(false);cin.tie(0);cout.tie(0);
#define pb push_back
#define pf push_front
#define popb pop_back
#define popf pop_front
#define fr front
#define bk back
#define fi first
#define se second
int n,p,q;
vector<int> a(2005);
int dp[2005][2005];
// motivation for DP:
/*
dp[i][j] = the min number of large cameras that we can use when we have taken i lanes using
j small cameras
*/
signed main() {
fastio();
cin>>n>>p>>q;
for(int i=0;i<n;i++){
cin>>a[i];
}
p=min(p,n);
q=min(q,n);
sort(a.begin(),a.begin()+n);
int l=1,r=1e9,ans=1e9;
while(l<r-1){
// binary searching on w
int mid=(l+r)/2;
for(int i=0;i<2005;i++){
for(int j=0;j<2005;j++){
dp[i][j]=inf;
}
}
dp[0][0]=0;
for(int i=0;i<n;i++){
for(int j=0;j<=p;j++){
// 1st case: the number of large cameras required > q
if(dp[i][j]>q) continue;
// suppose we have a w already (w=mid)
// suppose we take a small camera
// range: a[i]->a[i]+mid
int s_range=upper_bound(a.begin(),a.begin()+n,a[i]+mid-1)-a.begin();
dp[s_range][j+1]=min(dp[s_range][j+1],dp[i][j]);
int l_range=upper_bound(a.begin(),a.begin()+n,a[i]+2*mid-1)-a.begin();
dp[l_range][j]=min(dp[l_range][j],dp[i][j]+1);
}
}
bool flag=0;
for(int i=0;i<=p;i++){
if(dp[n][i]<=q){
flag=1;
break;
}
}
if(flag){
ans=min(ans,mid);
r=mid;
}
else{
l=mid;
}
}
cout<<ans;
}
