#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 102
int arr[N];
int dp[N][N][N];
int n;
int solve(int x,int p,int q,int w){
if(x>n)return 0;
if(dp[x][p][q]!=-1)return dp[x][p][q];
dp[x][p][q]=-2;
if(p){
for(int i=x+1;i<=n;i++){
if(arr[i]-arr[x]+1>w){
dp[x][p][q]=solve(i,p-1,q,w);
break;
}
if(i==n)dp[x][p][q]=0;
}
}
if(q&&dp[x][p][q]!=0){
for(int i=x+1;i<=n;i++){
if(arr[i]-arr[x]+1>w*2){
dp[x][p][q]=solve(i,p,q-1,w);
break;
}
if(i==n)dp[x][p][q]=0;
}
}
//cout<<x<<" "<<p<<" "<<q<<" "<<dp[x][p][q]<<endl;
return dp[x][p][q];
}
signed main(){
lalala;
int p,q;cin>>n>>p>>q;
p=min(n,p);
q=min(n,q);
arr[0]=-3;
for(int i=1;i<=n;i++)cin>>arr[i];
sort(arr,arr+n+1);
int l=1,r=1000000005;
int cev=-1;
while(l<=r){
int mid=(l+r)/2;
memset(dp,-1,sizeof(dp));
if(solve(1,p,q,mid)==0){
cev=mid;
r=mid-1;
}
else l=mid+1;
}
cout<<cev<<endl;
}
