#include <bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(), (x).end()
const int N = 2e3+5;
int a[N];
int main ()
{
ios::sync_with_stdio(false);
cin.tie(0);
int n, p, q;
cin >> n >> p >> q;
for (int i = 1; i <= n; i++) cin >> a[i];
sort(a+1,a+n+1);
if (p+q >= n) return cout << 1, 0;
int l = 1, r = 1e9, ans = -1;
while(l <= r){
int md = (l+r)>>1;
vector<vector<int>> dp(n+1, vector<int>(min(p+1,q+1), 1e9));
for (int i = 0; i <= min(p,q); i++) dp[0][i] = 0;
int pos1 = 1, pos2 = 1;
for (int i = 1; i <= n; i++){
for (int j = 0; j <= min(p,q); j++){
while(a[pos1] <= a[i]-md) pos1++;
while(a[pos2] <= a[i]-2*md) pos2++;
if (p <= q){
if (j) dp[i][j] = min(dp[i][j], dp[pos1-1][j-1]);
dp[i][j] = min(dp[i][j], dp[pos2-1][j]+1);
}else{
if (j) dp[i][j] = min(dp[i][j], dp[pos2-1][j-1]);
dp[i][j] = min(dp[i][j], dp[pos1-1][j]+1);
}
}
}
if (*min_element(all(dp[n])) <= max(p,q)){
ans = md;
r = md - 1;
}else l = md + 1;
}
cout << ans;
}
