#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;
int dp[2005][2005];
bool chick(int w,vector<int>&point){
vector<int>u(n+1),v(n+1);
for(int i=1;i<=n;i++){
u[i]=upper_bound(point.begin()+1,point.end(),point[i]-w)-point.begin()-1;
v[i]=upper_bound(point.begin()+1,point.end(),point[i]-2*w)-point.begin()-1;
}
for(int i=1;i<=n;i++){
for(int j=0;j<=min(n,k);j++){
if(j==0)dp[i][j]=dp[u[i]][j]+1;
else dp[i][j]=min(dp[u[i]][j]+1,dp[v[i]][j-1]);
}
}
return (dp[n][min(n,b)]<=k);
}
int32_t main(){
int ans;
cin>>n>>k>>b;
vector<int>point(n+1);
for(int i=1;i<=n;i++)cin>>point[i];
int l=1,r=N;
sort(point.begin()+1,point.end());
while(l<=r){
int mid=(l+r)>>1;
if(chick(mid,point)){
ans=mid;
r=mid-1;
}
else{
l=mid+1;
}
}
cout<<l<<endl;
}
