#include<bits/stdc++.h>
#define ll long long
const int nmax = 2e3+ 5, N = 1e6;
const ll oo = 1e18 + 1, base = 311;
const int lg = 19, M = 10;
const ll mod = 1e9 + 2277, mod2 = 1e9 + 5277;
#define pii pair<int, int>
#define fi first
#define se second
#define endl "\n"
#define debug(a, n) for(int i = 1; i <= n; ++i) cout << a[i] << ' '; cout << "\n";
using namespace std;
int n, p, q;
int a[nmax];
int dp[nmax][nmax];
void ckmax(int &a, int b){
a = max(a, b);
}
bool check(int mid){
memset(dp, -1,sizeof dp);
dp[0][0] = 0;
for(int i = 0; i <= p; ++i){
for(int j = 0; j <= q; ++j){
if(dp[i][j] == n) return 1;
if(dp[i][j] != -1 ){
int x = dp[i][j] + 1;
int it = upper_bound(a + x + 1, a + 1 + n, a[x] + mid - 1) - a - 1;
ckmax(dp[i + 1][j], it);
it = upper_bound(a + x + 1, a + 1 + n, a[x] + 2 * mid - 1) - a - 1;
ckmax(dp[i][j + 1], it);
}
}
}
return 0;
}
main(){
ios_base::sync_with_stdio(0);
cin.tie(0);cout.tie(0);
// freopen("code.inp", "r", stdin);
// freopen("code.out", "w", stdout);
cin >> n >> p >> q;
for(int i = 1; i <= n; ++i) cin >> a[i];
sort(a + 1, a + 1 + n);
if(p + q >= n) cout << 1, exit(0);
int l =1, r = 1e9, kq =-1;
while(l <= r){
int mid = r + l >> 1;
if(check(mid)){
kq = mid;
r = mid - 1;
}
else l = mid + 1;
}
cout << kq;
}
/*
a[mid] - a[x] > w
*/
