#include <bits/stdc++.h>
#define ll long long
#define pb push_back
#define endl "\n"
#define vec vector<ll>
#define vecvec vector<vector<ll>>
using namespace std;
/*#define FileName ""
string Ghhhh = ".in";
string Ghhhhh = ".out";
ifstream Girdi(FileName + Ghhhh);
ofstream Cikti(FileName + Ghhhhh);
#define cin Girdi
#define cout Cikti*/
const ll INF = 1e15;
ll n,a,b;
vector<ll> speed;
vector<ll> dp;
inline ll dp_func(ll node){
if(dp[node] != INF) return dp[node];
dp[node] = 0;
for(ll i = a ; i <= min(b,2*a) and node + i <= n; i++){
dp[node] = min(dp[node],max(speed[i+node-1] - speed[node], dp_func(node+i)));
}
return dp[node];
}
inline void solve(){
cin >> n >> a >> b;
speed.resize(n);
dp.resize(n,INF);
for(ll i = 0 ; i < n ; i++) cin >> speed[i];
sort(speed.begin(), speed.end());
cout << dp_func(0) << endl;
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
ll t = 1;
//cin >> t;
while(t--){
solve();
}
}
