#include<bits/stdc++.h>
//#include<gondola.h>
using namespace std;
#define rc(x) return cout<<x<<endl,0
#define pb push_back
#define dbg(x) cout << #x << '=' << x << '\n';
#define ll long long
#define int ll
#define sz size()
#define x first
#define y second
#define pi pair <int, int>
#define pii pair <int, pi>
#define vi vector <int>
const ll mod = 998244353;
int n, p, q, dp[2005][2005];
int w[2005];
bool check(int d){
for(int i=0; i<=n; i++){
for(int j=0; j<=p; j++) dp[i][j]=1e18;
}
dp[0][0]=0;
for(int j=1; j<=p; j++) dp[0][j]=0;
for(int i=0; i<n; i++){
int x=(upper_bound(w+1, w+n+1, w[i+1]+d-1)-w)-1;
int y=(upper_bound(w+1, w+n+1, w[i+1]+2*d-1)-w)-1;
for(int j=0; j<=p; j++){
if(j<p) dp[x][j+1]=min(dp[x][j+1], dp[i][j]);
dp[y][j]=min(dp[y][j], dp[i][j]+1);
}
}
/*if(d<=8)cout<<d<<"\n";
if(d<=8){
for(int i=0; i<=n; i++){
for(int j=0; j<=p; j++){
cout<<dp[i][j]<<" ";
}cout<<endl;
}
cout<<endl;
}*/
return (dp[n][p]<=q);
}
int32_t main(){
ios_base :: sync_with_stdio(0); cin.tie(); cout.tie();
cin>>n>>p>>q;
p=min(p, n);
for(int i=1; i<=n; i++){
cin>>w[i];
}
int l=0, r=1e9+1;
sort(w+1, w+n+1);
//w.pb(1000000001);
while(r-l>1){
int mid=(l+r)>>1;
if(check(mid)) r=mid;
else l=mid;
}
cout<<r;
}
