#include <bits/stdc++.h>
typedef long long ll;
#define pb push_back
#define MS(x,y) memset((x),(y),sizeof((x)))
const ll MN = 1000000007;
using namespace std;
ll n,p,q;
ll niz[2001],nizP[2001],nizQ[2001];
ll dp[2001][2001];
bool check(ll pos) {
for (ll i = 1; i<=n; i++) {
nizP[i] = (lower_bound(niz+1,niz+n+1,niz[i]+1*pos))-niz-1;
nizQ[i] = (lower_bound(niz+1,niz+n+1,niz[i]+2*pos))-niz-1;
for (ll j = 0; j<=i; j++) dp[i][j] = MN*MN;
}
for (ll i = 1; i<=n; i++) {
for (ll j = 0; j<i; j++) {
dp[nizP[i]][j] = min(dp[nizP[i]][j], dp[i-1][j]+1);
dp[nizQ[i]][j+1] = min(dp[nizQ[i]][j+1], dp[i-1][j]);
}
}
for (ll i = 0; i<=q; i++) {
if (dp[n][i] <= p) return true;
}
return false;
}
int main()
{
#if LOCAL_DEBUG
fstream cin("in.txt");
#endif
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin>>n>>p>>q;
if (p+q >= n) {
cout<<1<<endl;
return 0;
}
for (ll i = 1; i<=n; i++) cin>>niz[i];
sort(niz+1,niz+n+1);
ll left = 1, right = MN*MN;
while (left < right) {
ll mid = (left + right)/2;
if (check(mid)) right = mid;
else left = mid+1;
}
cout<<left<<endl;
}
