#include <iostream>
#include <algorithm>
#include <bitset>
using namespace std;
const int N_max = 1e6 + 5;
int n, A, B;
int v[N_max];
void reading(){
cin >> n >> A >> B;
for(int i = 1; i <= n; i++)
cin >> v[i];
sort(v + 1, v + n + 1);
}
bitset<N_max> propusi;
void reset(){
for(int i = 0; i < N_max; i++)
propusi[i] = 0;
}
int findNext(int poz){
while(propusi[poz] == 0 && poz <= n)poz++;
return poz;
}
bool verif(int i, int st, int md){
if(st <= n && !(v[i] - v[st] <= md && i - st + 1 <= B))
return 1;
return 0;
}
bool isPossible(int maxDifference){
reset();
propusi[1] = 1;
int st = 1; // startar
for(int i = 1; i <= n && st <= n; i++){
while(verif(i, st, maxDifference))
st = findNext(st + 1);
if(i - st + 1 < A) continue;
propusi[i + 1] = 1;
}
if(propusi[n + 1] == 1)
return 1;
return 0;
}
int main(){
reading();
int L = 0, R = N_max, sol = R;
while(L <= R){
int M = (L + R) / 2;
if(isPossible(M)){
sol = M;
R = M - 1;
}else
L = M + 1;
}
cout << sol;
}
