/** MIT License Copyright (c) 2018 Vasilyev Daniil **/
#include <bits/stdc++.h>
using namespace std;
#pragma GCC optimize("Ofast")
template<typename T> using v = vector<T>;
#define int long long
typedef string str;
typedef vector<int> vint;
#define rep(a, l, r) for(int a = (l); a < (r); a++)
#define pb push_back
#define sz(a) ((int) a.size())
const long long inf = 4611686018427387903; //2^62 - 1
#if 0 //FileIO
const string fileName = "";
ifstream fin ((fileName == "" ? "input.txt" : fileName + ".in" ));
ofstream fout((fileName == "" ? "output.txt" : fileName + ".out"));
#define get fin>>
#define put fout<<
#else
#define get cin>>
#define put cout<<
#endif
#define eol put endl
void read() {} template<typename Arg,typename... Args> void read (Arg& arg,Args&... args){get (arg) ;read(args...) ;}
void print(){} template<typename Arg,typename... Args> void print(Arg arg,Args... args){put (arg)<<" ";print(args...);}
void debug(){eol;} template<typename Arg,typename... Args> void debug(Arg arg,Args... args){put (arg)<<" ";debug(args...);}
int getInt(){int a; get a; return a;}
//code goes here
void run() {
int n, p, q;
read(n, p, q);
int a[n];
rep(i, 0, n)
get a[i];
sort(a, a + n);
if (p + q >= n) {
put 1;
return;
}
int l = 0, r = inf;
while (l + 1 < r) {
int w = (l + r) / 2;
int dp[n][p + 1];
int pointerForP = 0, pointerForQ = 0;
rep(i, 0, n) {
while (a[i] - a[pointerForP] >= w)
pointerForP++;
while (a[i] - a[pointerForQ] >= 2 * w)
pointerForQ++;
//debug(w, i, pointerForP, pointerForQ);
rep(j, 0, p + 1)
if (j) {
if (pointerForP == 0)
dp[i][j] = 0;
else if (pointerForQ == 0)
dp[i][j] = min(dp[pointerForP - 1][j - 1], 1ll);
else
dp[i][j] = min(dp[pointerForP - 1][j - 1], dp[pointerForQ - 1][j] + 1);
} else {
if (pointerForQ == 0)
dp[i][j] = 1;
else
dp[i][j] = dp[pointerForQ - 1][j] + 1;
}
}
int mn = inf;
rep(i, 0, p + 1)
mn = min(mn, dp[n - 1][i]);
if (mn > q)
l = w;
else
r = w;
}
put r;
}
int32_t main() {srand(time(0)); ios::sync_with_stdio(0); cin.tie(0); cout.tie(0); put fixed; put setprecision(15); run(); return 0;}
