#include<bits/stdc++.h>
using namespace std;
vector<int> a;
int n, p, q;
bool can(int w) {
vector<vector<int>> dp(n, vector<int>(p+1));
vector<int> small_dist(n), big_dist(n);
int SMALL=0, BIG=0;
for(int i=0; i<n; i++) {
if(a[0]>=a[i]-w+1) small_dist[i]=-1;
else {
while(a[SMALL]<a[i]-w+1) SMALL++;
small_dist[i]=--SMALL;
}
if(a[0]>=a[i]-2*w+1) big_dist[i]=-1;
else {
while(a[BIG]<a[i]-2*w+1) BIG++;
big_dist[i]=--BIG;
}
}
for(auto &p : dp) for(int &pp : p) pp=1e4;
dp[0][0]=1;
for(int i=1; i<=p; i++) dp[0][1]=0;
for(int i=1; i<n; i++) {
for(int j=0; j<=p; j++) {
SMALL=small_dist[i], BIG=big_dist[i];
if(j) {
if(SMALL==-1) dp[i][j]=0;
else dp[i][j]=min(dp[i][j], dp[SMALL][j-1]);
}
if(BIG==-1) dp[i][j]=min(dp[i][j], 1);
else dp[i][j]=min(dp[i][j], dp[BIG][j]+1);
}
}
for(int i=0; i<=p; i++) {if(dp[n-1][i]<=q) return 1;}
return 0;
}
int main() {
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
cin >> n >> p >> q;
a.resize(n);
for(int &p : a) cin >> p;
if(p+q>=n) {cout << "1\n"; return 0;}
sort(a.begin(), a.end());
int l=1, r=1e9, w=1e9;
while(l<=r) {
int mid=(l+r)/2;
if(can(mid)) w=mid, r=mid-1;
else l=mid+1;
}
cout << w << '\n';
return 0;
}
