#include<bits/stdc++.h>
#define int long long
using namespace std;
vector<int> a;
int n;
int binser(int x) {
int l=0, r=n-1, ans=0;
while(l<=r) {
int mid=(l+r)/2;
if(a[mid]<x) ans=mid, l=mid+1;
else r=mid-1;
}
return ans;
}
bool can(int w, int p, int q) {
int idx=0;
while(idx<n) {
if(p>1 && q) {
int BIG=binser(a[idx]+2*w);
if(BIG==n-1) return 1;
int SMALL=binser(a[idx]+w);
if(SMALL==n-1) return 1;
SMALL=binser(a[SMALL+1]+w);
if(SMALL==n-1) return 1;
if(SMALL>BIG) p-=2, idx=SMALL;
else q--, idx=BIG;
} else if(p && q) {
int BIG=binser(a[idx]+2*w), SMALL=binser(a[idx]+w);
if(BIG==n-1 || SMALL==n-1) return 1;
if(BIG==SMALL) p--, idx=SMALL;
else q--, idx=BIG;
} else if(p) idx=binser(a[idx]+w), p--;
else if(q) idx=binser(a[idx]+2*w), q--;
else return 0;
idx++;
}
return 1;
}
signed main() {
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
int p, q; cin >> n >> p >> q;
a.resize(n);
for(int &p : a) cin >> p;
sort(a.begin(), a.end());
int l=1, r=1e9, w=1e9;
while(l<=r) {
int mid=(l+r)/2;
if(can(mid, p, q)) w=mid, r=mid-1;
else l=mid+1;
}
cout << w << '\n';
return 0;
}
