#include <bits/stdc++.h>
using namespace std;
#define vi vector<int>
#define vll vector<long long>
#define pb push_back
using ll= long long;
#define fast_io ios::sync_with_stdio(0); cin.tie(0)
#define inpint(x) int x; cin>>x
#define inpll(x) long long x; cin>>x
#define fl(i, n) for(int i=0; i<n; i++)
#define flo(i, n) for(int i=1; i<=n; i++)
#define int long long
#define pi pair<int, int>
#define mp make_pair
#define ld long double
const int MOD = 7 + (int)1e9;
const int INF = (int)1e18;
//
int n, p, q;
int a[2005]{};
bool check(int w)
{
int dp[p+1][q+1]{};
//p small q large
for(int i=0; i<=p; i++)
{
for(int j=0; j<=q; j++)
{
//check p, q-1 and p-1, q
if(j-1>=0)
{
int x = dp[i][j-1];
auto it = upper_bound(a+1, a+n+1, x);
int y = *it;
int z = y + (2*w) - 1;
it = upper_bound(a+1, a+n+1, z);
it--;
int t = *it;
dp[i][j] = max(dp[i][j], t);
}
if(i-1>=0)
{
int x = dp[i-1][j];
auto it = upper_bound(a+1, a+n+1, x);
int y = *it;
int z = y + (w) - 1;
it = upper_bound(a+1, a+n+1, z);
it--;
int t = *it;
dp[i][j] = max(dp[i][j], t);
}
if(dp[i][j]>=a[n]) return true;
}
}
return false;
}
void solve()
{
cin>>n>>p>>q;
for(int i=1; i<=n; i++)
{
cin>>a[i];
}
sort(a+1, a+n+1);
int low = 1;
int high = INF;
if(p+q>=n)
{
cout<<1;
return;
}
while(high>low)
{
int mid = (high+low)/2;
if(check(mid)) high = mid;
else low = mid+1;
}
assert(high==low);
cout<<high;
}
signed main()
{
fast_io;
int t=1;
//cin>>t;
while(t--)
{
solve();
}
cout<<endl;
}
