#include <bits/stdc++.h>
using namespace std;
#define name "ojuz"
#define MAXN 2003
#define pb push_back
#define pf push_front
#define ll long long
#define ii pair<int, int>
#define fs first
#define sc second
#define ill pair<int, ll>
#define lli pair<ll, int>
#define llll pair<ll, ll>
#define all(v) v.begin(),v.end()
#define uni(v) v.erase(unique(all(v)),v.end())
#define bit(n,i) (((n)>>(i))&1)
#define FOR(i,a,b) for (int i=(a),_b=(b); i<=_b; i++)
#define FORD(i,a,b) for (int i=(a),_b=(b); i>=_b; i--)
#define MASK(i) (1LL<<(i))
const int INF=1e9;
const int MOD=1e9+7;
void add(int &u, int v){
u+=v;
if (u>=MOD) u-=MOD;
}
void sub(int &u, int v){
u-=v;
if (u<0) u+=MOD;
}
void minimize(int &u, int v){
u=min(u,v);
}
void maximize(int &u, int v){
u=max(u,v);
}
long long Rand(long long l, long long r){
ll tmp=0;
FOR(i,1,4) tmp=((tmp<<15)^(((1<<15)-1)&rand()));
return l+tmp%(r-l+1);
}
int n,p,q;
int a[MAXN];
int f[MAXN],g[MAXN];
int dp[MAXN][MAXN];
bool check(int w){
f[1]=1;
FOR(i,2,n){
f[i]=f[i-1];
while (a[i]-a[f[i]]>=w) ++f[i];
}
g[1]=1;
FOR(i,2,n){
g[i]=g[i-1];
while (a[i]-a[g[i]]>=2*w) ++g[i];
}
FOR(i,0,n) FOR(j,0,p) dp[i][j]=INF;
dp[0][0]=0;
FOR(i,1,n){
FOR(j,0,p){
if (j>=1) minimize(dp[i][j],dp[f[i]-1][j-1]);
minimize(dp[i][j],dp[g[i]-1][j]+1);
}
}
FOR(j,0,p){
if (dp[n][j]<=q) return 1;
}
return 0;
}
int main()
{
ios::sync_with_stdio(0), cin.tie(0), cout.tie(0);
cin>>n>>p>>q;
FOR(i,1,n) cin>>a[i];
if (p+q>=n){
cout<<1;
return 0;
}
sort(a+1,a+n+1);
int l=1,r=INF,res=-1;
while (l<=r){
int mid=(l+r)/2;
if (check(mid)){
r=mid-1;
res=mid;
}
else l=mid+1;
}
cout<<res;
return 0;
}
