#include <bits/stdc++.h>
using namespace std;
#define int long long
#define FOR(I, L, R) for(int I(L) ; I <= (int)R ; ++I)
#define FOD(I, R, L) for(int I(R) ; I >= (int)L ; --I)
#define FOA(I, A) for(auto &I : A)
#define print(A,L,R) FOR(OK, L, R){if(A[OK]<=-oo / 10||A[OK]>=oo)cout<<"- ";else cout<<A[OK]<<' ';}cout<<'\n';
#define prints(A) FOA(OK, A){cout<<OK<<' ';}cout << '\n';
#define printz(A,L,R) FOR(OK, 0, L){FOR(KO, 0, R){if(A[OK][KO]>-oo&&A[OK][KO]<oo)cout<<A[OK][KO]<<' ';else cout << "- ";} cout << '\n';}cout << '\n';
#define fs first
#define sd second
#define ii pair<int,int>
#define iii pair<int, ii>
#define all(A) A.begin(), A.end()
#define quickly cin.tie(0) -> ios_base::sync_with_stdio(0);
const int N = 2000 + 5;
const int mod = 1e9 + 7;
const int oo = 1e18;
int n, k, p, q;
int dp[N][N], a[N];
int l1[N], l2[N];
int calc(int w){
memset(dp, 0x3f, sizeof dp);
FOR(j, 0, p){
dp[0][j] = 0;
FOR(i, 1, n){
if(j != 0) dp[i][j] = dp[l1[i] - 1][j - 1];
dp[i][j] = min(dp[i][j], dp[l2[i] - 1][j] + 1);
}
}
return dp[n][p] <= q;
}
signed main(){ quickly
cin >> n >> p >> q;
FOR(i, 1, n){
cin >> a[i];
}
if(p + q >= n){
cout << 1;
return 0;
}
sort(a + 1, a + 1 + n);
int l = 1, r = a[n];
int ans = 0;
while(l <= r){
int mid = (l + r) >> 1;
int lq = 1, lp = 1;
FOR(i, 1, n){
while(a[i] - mid + 1 > a[lp]){
++lp;
}
while(a[i] - 2 * mid + 1 > a[lq]){
++lq;
};
l1[i] = lp;
l2[i] = lq;
}
if(calc(mid)){
r = mid - 1;
ans = mid;
}
else{
l = mid + 1;
}
}
cout << ans;
}
