#include <bits/stdc++.h>
using namespace std;
#define f first
#define ss second
#define ina insert
#define pb push_back
int n,p,q;
vector<int>x(2005);
bool check(int w){
int dp[n+1][p+1];
for(int i=0; i<=n; i++){
for(int j=0; j<=p; j++){
if(i==0){
dp[i][j]=0;
}
else dp[i][j]=1e8;
}
}
int l_pa=0;
int l_did=0;
//dp[0][0]=1;
for(int i=1; i<=n; i++){
while(l_pa+1<=n && x[i]-w>=x[l_pa+1])l_pa++;
while(l_did+1<=n && x[i]-2*w>=x[l_did+1])l_did++;
for(int j=0; j<=p; j++){
if(j>=1)dp[i][j]=min(dp[l_pa][j-1],dp[i][j]);
dp[i][j]=min(dp[i][j],dp[l_did][j]+1);
//cout<<dp[i][j]<<" ";
}
//cout<<endl;
}
if(dp[n][p]<=q){
return true;
}
return false;
}
signed main(){
cin>>n>>p>>q;
//x.resize(n + 1);
for(int i=1; i<=n; i++){
cin>>x[i];
}
x[0]=-1;
sort(x.begin(),x.end());
int l=1,r=1e9;
int ans=-1;
while(l<=r){
int mid=(l+r)/2;
int h=check(mid);
//cout<<h<<" "<<mid<<endl;
if(h){
r=mid-1;
ans=mid;
}
else{
l=mid+1;
}
}
cout<<ans<<endl;
}
