#include <bits/stdc++.h>
using namespace std;
#define int long long
const int N = 2e3;
int n, p, q, arr[N + 5];
pair<int, int> dp[N + 5][2];
signed main() {
ios::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> p >> q;
for (int i = 1; i <= n; i++) cin >> arr[i];
sort(arr + 1, arr + n + 1);
int l = 1, r = 1e9, ans = 1e9;
while (l <= r) {
int m = (l + r)/2;
for (int i = 1; i <= n; i++) dp[i][0] = dp[i][1] = {-1, -1};
dp[0][0] = dp[0][1] = {q, p};
for (int i = 1; i <= n; i++) {
for (int j = 1; j <= i; j++) {
for (int k = 0; k < 2; k++) {
int prevQ = dp[j - 1][k].first, prevP = dp[j - 1][k].second;
if (prevQ && arr[i] - arr[j] + 1 <= 2*m) dp[i][0] = max(dp[i][0], {prevQ - 1, prevP});
if (prevP && arr[i] - arr[j] + 1 <= m) dp[i][1] = max(dp[i][1], {prevQ, prevP - 1});
}
}
}
if (dp[n][0].first != -1 || dp[n][1].first != -1) ans = m, r = m - 1;
else l = m + 1;
}
cout << ans << '\n';
return 0;
}
