#include<bits/stdc++.h>
using namespace std;
#pragma GCC optimize("O3,unroll-loops")
#pragma GCC target("avx2,bmi,bmi2,sse4,sse4.2,lzcnt,popcnt")
using pii = pair<int, int>;
#define X first
#define Y second
#define pb push_back
#define all(x) x.begin(), x.end()
#define SZ(x) int(x.size())
const int MXN = 2e3+5;
int n, P, Q, a[MXN], dp[MXN][MXN];
int32_t main() {
cin.tie(0); cout.tie(0); ios_base::sync_with_stdio(0);
cin >> n >> P >> Q; P = min(P, n); Q = min(Q, n);
for(int i=0; i<n; i++) cin >> a[i];
sort(a, a+n);
auto check = [&](int w) {
int lw=-1, l2w=-1;
for(int i=0; i<n; i++) {
while(a[i]-a[lw+1]+1>w) lw++;
while(a[i]-a[l2w+1]+1>w+w) l2w++;
for(int j=0; j<=P; j++) {
dp[i][j] = j ? (lw==-1 ? 0 : dp[lw][j-1]) : 1e9;
dp[i][j] = min(dp[i][j], (l2w==-1 ? 0 : dp[l2w][j]) + 1);
}
}
return *min_element(dp[n-1], dp[n-1]+P+1) <= Q;
};
int l=0, r=1e9;
while(r-l>1)
(check(l+r>>1) ? r : l) = l+r>>1;
cout << r << '\n';
return 0;
}
