#include<bits/stdc++.h>
using namespace std;
#define lalala ios_base::sync_with_stdio(false);cin.tie(NULL);cout.tie(NULL);
#define int long long int
#define endl '\n'
#define N 2005
#define pb push_back
vector<int> arr;
int dp[N][N];
int solve(int n,int p,int q,int w){
dp[0][0]=-1;
for(int i=0;i<=p;i++){
for(int j=0;j<=q;j++){
dp[i][j]=-1;
if(i){
int deg=upper_bound(arr.begin(),arr.end(),arr[dp[i-1][j]+1]+w-1 )-arr.begin();
deg-=1;
dp[i][j]=max(dp[i][j],deg);
}
if(j){
int deg=upper_bound(arr.begin(),arr.end(),arr[dp[i][j-1]+1]+w*2-1 )-arr.begin();
deg-=1;
dp[i][j]=max(dp[i][j],deg);
}
//cout<<i<<" "<<j<<": "<<dp[i][j]<<endl;
if(dp[i][j]>=n-1)return 1;
}
}
return 0;
}
signed main(){
lalala;
int n,p,q;cin>>n>>p>>q;
for(int i=1;i<=n;i++){
int a;cin>>a;
arr.pb(a);
}
sort(arr.begin(),arr.end());
int l=1,r=1000000105;
int cev=-1;
//l=4;r=4;
while(l<=r){
int mid=(l+r)/2;
//cout<<mid<<endl;
if(solve(n,p,q,mid)){
cev=mid;
r=mid-1;
}
else l=mid+1;
}
cout<<cev<<endl;
}
