#include <bits/stdc++.h>
#define f0(i, n) for(int i(0); i < (n); i++)
#define f1(i, n) for(int i(1); i <= n; i++)
using namespace std;
typedef long long ll;
const int N = 2002;
int n, p, q, a[N], d1[N], d2[N], f[N][N];
bool check(int dist){
/// f(i, j) den i, dung j camera nho
f1(i, n){
d1[i] = lower_bound(a + 1, a + n + 1, a[i] - dist + 1) - a;
d2[i] = lower_bound(a + 1, a + n + 1, a[i] - 2*dist + 1) - a;
}
f0(i, p + 1) f[0][i] = q;
f1(i, n) f0(j, p + 1) f[i][j] = -1e9;
f1(i, n){
f0(j, p + 1){
if(j==0){
int x = max(d2[i], 0);
f[i][j] = f[x - 1][j] - 1;
continue;
}
int x = max(d1[i] - 1, 0);
f[i][j] = f[x][j - 1];
x = max(d2[i] - 1, 0);
f[i][j] = max(f[i][j], f[x][j] - 1);
}
}
f0(j, p + 1) if(f[n][j] >= 0) return 1;
return 0;
}
int main(){
ios_base::sync_with_stdio(0);
cin >> n >> p >> q;
f1(i, n) cin >> a[i];
sort(a + 1, a + n + 1);
if(p + q >= n){
cout << 1;
return 0;
}
int l = 0, r = 1e9 + 10, ans = 0;
while(l <= r){
int mid = (l + r)/2;
if(check(mid)) r = mid - 1, ans = mid;
else l = mid + 1;
}
cout << ans;
}
