#include <bits/stdc++.h>
#define int long long
#define ff first
#define ss second
#define pb push_back
#define all(x) x.begin(),x.end()
using namespace std;
signed main(){
ios_base::sync_with_stdio();
cin.tie(0);cout.tie(0);
int n,p,q;
cin>>n>>p>>q;
p=min(n,p);
q=min(n,q);
vector <int> a(n);
for(int i=0;i<n;i++)cin>>a[i];
sort(all(a));
int l=0,r=1e10;
while(l+1<r){
int md=(l+r)/2;
bool ok=0;
vector <vector <int> > dp(n+1,vector <int> (p+1,1e9));
for(int i=0;i<=p;i++)dp[0][i]=0;
for(int i=1;i<=n;i++){
auto pos1=lower_bound(all(a),a[i-1]-md*2+1)-a.begin();
auto pos2=lower_bound(all(a),a[i-1]-md+1)-a.begin();
for(int j=0;j<=p;j++){
dp[i][j]=min(dp[i][j],dp[pos1][j]+1);
if(j>0)dp[i][j]=min(dp[i][j],dp[pos2][j-1]);
}
}
if(dp[n][p]<=q)ok=1;
if(ok)r=md;
else l=md;
}
cout<<r<<"\n";
}
/*
13 3 2 33
66
99
10
83
68
19
83
93
53
15
66
75
*/
