#include <bits/stdc++.h>
using namespace std;
const int N = 2e3+10;
int n, p, q, a[N];
int dp[N][N];
bool valid(int w){
for(int i = 1; i <= n; ++i){
int large = upper_bound(a+1, a+n+1, a[i]-2*w) - (a+1);
int small = upper_bound(a+1, a+n+1, a[i]-w) - (a+1);
for(int j = 0; j <= q; ++j){
dp[i][j] = 1e9;
dp[i][j] = min( (large == 0 || j == 0) ? (j == 0 ? N : 0) : dp[large][j-1],
(small == 0) ? 1 : dp[small][j]+1);
}
}
return dp[n][q] <= p;
}
int main(){
ios_base::sync_with_stdio(false);
cin.tie(nullptr);
cin >> n >> p >> q;
if(p+q >= n){
cout << 1 << '\n';
return 0;
}
for(int i = 1; i <= n; ++i) cin >> a[i];
sort(a+1, a+n+1);
int l = 1, r = 1e9;
while(l < r){
int mid = (l+r)>>1;
if(valid(mid)) r = mid;
else l = mid+1;
}
cout << r << '\n';
}
