#include <bits/stdc++.h>
using namespace std;
using ll = long long;
const int maxn = 2005;
int N, P, Q;
ll A[maxn];
int dp[maxn][maxn];
//[i-1'th one covered][# small used] = # of large needed
//
int jmpSmall[maxn], jmpBig[maxn];
int f(int i, int j) {
if (i > N) return 0;
int& res = dp[i][j];
if (res != -1) return res;
//take big one
res = 1+f(jmpBig[i],j);
if (j < P) res = min(res,f(jmpSmall[i],j+1));
return res;
}
bool poss(ll w) {
memset(dp,-1,sizeof dp);
int pt = 0;
for (int i = 1; i <= N; i++) {
while (pt <= N && A[pt] < A[i]+w) pt++;
jmpSmall[i] = pt;
}
pt = 0;
for (int i = 1; i <= N; i++) {
while (pt <= N && A[pt] < A[i]+2*w) pt++;
jmpBig[i] = pt;
}
return f(1,0) <= Q;
}
int main() {
ios_base::sync_with_stdio(false); cin.tie(NULL);
cin >> N >> P >> Q;
for (int i = 1; i <= N; i++) {
cin >> A[i];
}
sort(A+1,A+N+1);
ll lo = 0, hi = 1e9+9;
while (lo + 1 < hi) {
ll w = (lo+hi)/2;
if (poss(w)) hi = w;
else lo = w;
}
cout << hi << endl;
}
