///TRAN THAI BAO :3
#include <iostream>
#include <cstdio>
#include <algorithm>
#include <vector>
using namespace std;
#define maxN 100007
int n, p, q;
vector<long long>a;
bool check(int w)
{
int pL = p, qL = q;
int i = 0;
while(i < n)
{
if(pL == 0 && qL == 0)
return false;
long long nexPos = -1;
if(qL > 0)
{
vector<long long>::iterator it = lower_bound(a.begin(), a.end(), a[i]+w);
if((it != a.end() && (long long)*it - a[i] + 1 <= 2*w) || pL == 0)
{
nexPos = a[i] + 2ll*w;
}
}
if(nexPos != -1)
{
qL--;
}
else
{
nexPos = a[i]+w;
pL--;
}
while(i < n && a[i] < nexPos)
i++;
}
return true;
}
void solve()
{
cin >> n >> p >> q;
for(int i = 1; i <= n; i++)
{
int x;
cin >> x;
a.push_back(x);
}
sort(a.begin(), a.end());
int lo = 1, hi = 1000000000, mid, ans = 1000000000;
while(lo <= hi)
{
mid = (lo+hi)/2;
if(check(mid))
{
ans = min(ans, mid);
hi = mid-1;
}
else lo = mid+1;
}
cout << ans;
}
int main()
{
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
solve();
return 0;
}
