#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int INF = 1e8;
const int MAX_N = 2005;
int dp[MAX_N][MAX_N], a[MAX_N], nxtP[MAX_N], nxtQ[MAX_N];
int N, P, Q;
int f(int idx, int remQ){
if(remQ < 0) return INF;
if(idx > N) return 0;
auto &cur = dp[idx][remQ];
if(cur != -1) return cur;
cur = min(f(nxtP[idx], remQ) + 1, f(nxtQ[idx], remQ - 1));
return cur;
}
bool check(int x){
int j = 2, k = 2;
for(int i = 1; i <= N; i++){
while(j <= N && a[j] - a[i] + 1 <= x) j++;
while(k <= N && a[k] - a[i] + 1 <= 2*x) k++;
nxtP[i] = j;
nxtQ[i] = k;
}
memset(dp, -1, sizeof(dp));
return (f(1, Q) <= P);
}
int main(){
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> N >> P >> Q;
P = min(P, N); Q = min(Q, N);
for(int i = 1; i <= N; i++) cin >> a[i];
sort(a + 1, a + N + 1);
ll ans = -1, l = 1, r = 1e9;
while(l <= r){
int mid = (l + r)/2;
if(check(mid)){
ans = mid;
r = mid - 1;
} else{
l = mid + 1;
}
}
cout << ans << '\n';
return 0;
}
