// EXPLOSION!
#define _CRT_SECURE_NO_WARNINGS
#include<bits/stdc++.h>
#include<unordered_set>
#include<unordered_map>
#include<chrono>
using namespace std;
typedef pair<int, int> pii;
typedef long long ll;
typedef pair<ll, ll> pll;
typedef long double ld;
typedef vector<int> vi;
typedef vector<ll> vll;
typedef vector<pair<int, int>> vpi;
typedef vector<pair<ll, ll>> vpll;
#define FOR(i,a,b) for (int i = (a); i < (b); ++i)
#define F0R(i,a) FOR(i,0,a)
#define ROF(i,a,b) for (int i = (b)-1; i >= (a); --i)
#define R0F(i,a) ROF(i,0,a)
#define trav(a,x) for (auto& a: x)
#define pb push_back
#define mp make_pair
#define rsz resize
#define sz(x) int(x.size())
#define all(x) x.begin(),x.end()
#define f first
#define s second
#define cont continue
#define endl '\n'
//#define ednl '\n'
#define test int testc;cin>>testc;while(testc--)
#define pr(a, b) trav(x,a)cerr << x << b; cerr << endl;
#define message cout << "Hello World" << endl;
const int dx[4] = { 1,0,-1,0 }, dy[4] = { 0,1,0,-1 }; // for every grid problem!!
const ll linf = 4000000000000000000LL;
const ll inf = 1000000007;//998244353
void pv(vi a) { trav(x, a)cout << x << " "; cout << endl; }void pv(vll a) { trav(x, a)cout << x << " "; cout << endl; }void pv(vector<vi>a) {
F0R(i, sz(a)) { cout << i << endl; pv(a[i]); cout << endl; }
}void pv(vector<vll>a) { F0R(i, sz(a)) { cout << i << endl; pv(a[i]); }cout << endl; }void pv(vector<string>a) { trav(x, a)cout << x << endl; cout << endl; }
void setIO(string s) {
ios_base::sync_with_stdio(0); cin.tie(0);
#ifdef arwaeystoamneg
if (sz(s))
{
freopen((s + ".in").c_str(), "r", stdin);
if (s != "test1")
freopen((s + ".out").c_str(), "w", stdout);
}
#endif
}
int n, p, q;
const int MAX = 2005;
int a[MAX], dp[MAX][MAX], ne[MAX], ne1[MAX];
int check(int w)
{
// dp[i][j] is the minimum number of Q parts needed to cover the first i sections with j P parts.
F0R(i, n + 1)F0R(j, p + 1)dp[i][j] = inf;
dp[0][0] = 0;
int ptr = 0;
F0R(i, n)
{
while (ptr < n && a[ptr] - a[i] <= w - 1)ptr++;
ne[i] = ptr;
}
ptr = 0;
F0R(i, n)
{
while (ptr < n && a[ptr] - a[i] <= 2 * w - 1)ptr++;
ne1[i] = ptr;
}
F0R(i, n)
{
F0R(j, p + 1)
{
if (j != p)
{
int it = ne[i];
dp[it][j + 1] = min(dp[it][j + 1], dp[i][j]);
}
if (dp[i][j] < q)
{
auto it = ne1[i];
dp[it][j] = min(dp[it][j], dp[i][j] + 1);
}
}
}
F0R(i, p + 1)if (dp[n][i] <= q)return 1;
return 0;
}
int main()
{
setIO("");
cin >> n >> p >> q;
F0R(i, n)cin >> a[i];
sort(a, a + n);
if (p + q >= n)
{
cout << 1 << endl;
return 0;
}
int l = 1, r = 1e9;
while (l < r)
{
int m = (l + r) / 2;
if (check(m))
r = m;
else
l = m + 1;
}
cout << l << endl;
}
