#include <cmath>
#include <cstdio>
#include <vector>
#include <iostream>
#include <algorithm>
#include <cstdint>
//#include <bits/stdc++.h>
#define int long long
using namespace std;
const int N=1e9+7;
int n,k,b;
bool chick(int w,vector<int>&point){
int i=0;
bool f=1;
int kk=k,bk=b,onceb=0,oncek=0;//indexleri
while(i<n){
if(bk>0){
int end=point[i]+2*w-1;
while(i<n && point[i]<=end)i++;
bk--;
}
else if(kk>0){
int end=point[i]+w-1;
while(i<n && point[i]<=end)i++;
kk--;
}
else{
f=0;
break;
}
}
if(f)return 1;
kk=k,bk=b,i=0;
while(i<n){
if(kk>0){
int end=point[i]+w-1;
while(i<n && point[i]<=end)i++;
kk--;
}
else if(bk>0){
int end=point[i]+2*w-1;
while(i<n && point[i]<=end)i++;
bk--;
}
else{
f=0;
break;
}
}
if(f)return 1;
else return 0;
}
int32_t main(){
int ans;
cin>>n>>k>>b;
vector<int>point(n);
for(int i=0;i<n;i++)cin>>point[i];
int l=1,r=N;
sort(point.begin(),point.end());
while(l<r){
int mid=(l+r)>>1;
if(chick(mid,point)){
ans=mid;
r=mid;
}
else{
l=mid+1;
}
}
cout<<l<<endl;
}
