#include <bits/stdc++.h>
using namespace std;
#define FAST_IO ios_base::sync_with_stdio(0); cin.tie(nullptr)
#define FOR(i, a, b) for (int i = (a); i <= (b); i++)
#define pb push_back
typedef long long ll;
const int MAXN = 1000100;
const ll INF = 1e16;
int n, a, b;
ll dp[MAXN], t[MAXN];
vector<ll> ts;
int main()
{
FAST_IO;
//ifstream cin ("lmio_2018_3e2_plaukimo_varzybos_vyr.in");
//ofstream cout ("lmio_2018_3e2_plaukimo_varzybos_vyr.out");
cin >> n >> a >> b;
FOR(i, 1, n) {ll x; cin >> x; ts.pb(x);}
sort(ts.begin(), ts.end());
FOR(i, 0, n-1) t[i+1] = ts[i];
FOR(i, 1, n) dp[i] = INF;
FOR(i, 1, n) FOR(j, max(0,i-b), max(0,i-a)) dp[i] = min(dp[i], max(dp[j],t[i]-t[j+1]));
cout << dp[n] << "\n";
return 0;
}
