#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int a, b, c;
vector<ll> z;
int K;
int count_segments(int w, vector<pair<int,int>>& segs){
segs.clear();
int i = 0;
while(i < a){
int r = upper_bound(z.begin(), z.end(), z[i] + w - 1) - z.begin() - 1;
segs.emplace_back(i, r);
i = r + 1;
}
return segs.size();
}
int main(){
ios::sync_with_stdio(false);
cin.tie(NULL);
cin >> a >> b >> c;
K = b + c;
z.resize(a);
for(int i = 0; i < a; i++) cin >> z[i];
sort(z.begin(), z.end());
int L = 1, R = z.back() - z.front() + 1, best = R;
vector<pair<int,int>> best_segs, tmp;
while(L <= R){
int mid = (L + R) >> 1;
int need = count_segments(mid, tmp);
if(need <= K){
best = mid;
best_segs = tmp;
R = mid - 1;
} else {
L = mid + 1;
}
}
while((int)best_segs.size() < K)
best_segs.emplace_back(-1,-1);
vector<int> lens(K);
for(int i = 0; i < K; i++){
auto [l,r] = best_segs[i];
if(l == -1) lens[i] = 0;
else lens[i] = z[r] - z[l] + 1;
}
sort(lens.begin(), lens.end(), greater<int>());
for(int i = 0; i < c; i++){
int x = lens[i];
lens[i] = (x + 1) / 2;
}
int answer = *max_element(lens.begin(), lens.end());
cout << answer << "\n";
return 0;
}
