#include <bits/stdc++.h>
using namespace std;
template <class T> bool mini(T &x, const T &y) { return y < x ? x = y, 1 : 0; }
template <class T> bool maxi(T &x, const T &y) { return y > x ? x = y, 1 : 0; }
const int N = 2005;
int n, p, q, dp[N][N], f[N], g[N];
long long a[N];
bool ok(int x) {
for (int i = 1; i <= n; i++) {
f[i] = upper_bound(a + 1, a + n + 1, a[i] + x - 1) - a;
g[i] = upper_bound(a + 1, a + n + 1, a[i] + 2 * x - 1) - a;
}
f[n + 1] = g[n + 1] = n + 1;
for (int i = 0; i <= p; i++)
for (int j = 0; j <= q; j++) {
dp[i][j] = 1;
if (i) maxi(dp[i][j], f[dp[i - 1][j]]);
if (j) maxi(dp[i][j], g[dp[i][j - 1]]);
}
return dp[p][q] > n;
}
int main() {
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> p >> q;
for (int i = 1; i <= n; i++) cin >> a[i];
sort(a + 1, a + n + 1);
n = unique(a + 1, a + n + 1) - a - 1;
mini(p, n);
mini(q, n);
int l = 1, r = (a[n] + 1) >> 1;
while (l <= r) {
int m = (l + r) >> 1;
if (ok(m)) r = m - 1;
else l = m + 1;
}
cout << l;
}
