#include <bits/stdc++.h>
using namespace std;
#ifdef DEBUG
auto&operator<<(auto &o, pair<auto, auto> p) {o << "(" << p.first << ", " << p.second << ")"; return o;}
auto operator<<(auto &o, auto x)->decltype(x.end(), o) {o<<"{"; for(auto e : x) o<<e<<", "; return o<<"}";}
#define debug(X) cerr << "["#X"]: " << X << '\n';
#else
#define cerr if(0)cout
#define debug(X) ;
#endif
#define ll long long
#define ld long double
#define all(v) (v).begin(), (v).end()
#define FOR(i,l,r) for(int i=(l);i<=(r);++i)
#define ROF(i,r,l) for(int i=(r);i>=(l);--i)
#define REP(i,n) FOR(i,0,(n)-1)
#define ssize(x) int(x.size())
#define fi first
#define se second
#define mp make_pair
#define eb emplace_back
int main() {
ios_base::sync_with_stdio(false); cin.tie(nullptr);
int n, p, q;
cin >> n >> p >> q;
vector<int> a(n);
REP(i, n) cin >> a[i];
sort(all(a));
if (p+q >= n) {cout << 1 << '\n'; return 0;}
const int inf = 1e9;
auto ok = [&](int w) {
vector dp(n+1, vector(p+1, 0));
auto bs = [&](int x) {
int low = -1, high = n;
while (high-low > 1) {
int mid = (high+low)/2;
if (a[mid] >= x) high = mid;
else low = mid;
}
return high;
};
FOR(i, 1, n) {
int p1 = bs(a[i-1]-w+1), p2 = bs(a[i-1]-2*w+1);
FOR(j, 0, p) {
dp[i][j] = min(j-1>=0?dp[p1][j-1]:inf, dp[p2][j]+1);
}
}
return dp[n][p] <= q;
};
int low = 0, high = int(1e9)+1;
while (high-low > 1) {
int mid = (high+low)/2;
if (ok(mid)) high = mid;
else low = mid;
}
cout << high << '\n';
return 0;
}
