#include <bits/stdc++.h>
#include <ext/pb_ds/detail/standard_policies.hpp>
#include <ext/pb_ds/assoc_container.hpp> // Common file
#include <ext/pb_ds/tree_policy.hpp> // Including tree_order_statistics_node_update
#define f first
#define s second
#define pb push_back
#define mp make_pair
#define clr(dp,i) memset(dp,i,sizeof(dp))
#define opt ios_base::sync_with_stdio(NULL);cin.tie(NULL);cout.tie(NULL);
using namespace std;
using namespace __gnu_pbds;
//typedef tree<int, null_type, less<int>, rb_tree_tag,
//tree_order_statistics_node_update> oset;
typedef long long ll;
typedef long double ld;
typedef unsigned long long ull;
typedef pair<int, int> pii;
const long long mod = 1e9+7;
const ld pi = 3.14159265358979323846264338327950288;
//==================================================
int n, p, q, w, ans, a[2001];
int dp[2002][2002];
int check(int i=0, int remp=p, int mx = -1)
{
if(i == n)
return 0;
if(mx > a[i])
return check(i+1, remp, mx);
int &ret = dp[i][remp];
if(ret != -1)
return ret;
if(n-i <= remp)
return 0;
ret = check(i+1, remp, a[i] + 2*w)+1;
if(remp)
ret = min(check(i+1, remp-1, a[i]+w), ret);
return ret;
}
int main()
{
opt;
cin >> n >> p >> q;
for(int i=0; i<n; i++)
cin >> a[i];
sort(a, a+n);
if(p+q >= n)
{
cout << 1 << endl;
return 0;
}
int s = 1, e = 1e9;
while(s <= e)
{
clr(dp, -1);
int mid = (s+e)/2;
w = mid;
if(check() <= q)
ans = mid, e = mid-1;
else
s = mid+1;
}
cout << ans << endl;
}
