#include <bits/stdc++.h>
using namespace std;
const int MAXN = 2005;
int a[MAXN], dp[MAXN][MAXN], n, p, q;
bool test(int w){
for(int i = n; i >= 1; i--){
int nxtp = upper_bound(a+1,a+1+n, a[i]+w-1)-a;
int nxtq = upper_bound(a+1,a+1+n, a[i]+2*w-1)-a;
for(int qtdp = 0; qtdp <= p; qtdp++){
dp[i][qtdp] = dp[nxtq][qtdp]+1;
if(qtdp > 0)dp[i][qtdp] = min(dp[i][qtdp], dp[nxtp][qtdp-1]);
}
}
return dp[1][p] <= q;
}
signed main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cin>>n>>p>>q;
for(int i = 1; i <= n; i++)cin>>a[i];
sort(a+1,a+1+n);
a[n+1] = 2*1e9;
int l = 0, r = 5*1e8;
while(l != r){
int mid = (l+r)/2;
if(test(mid))r = mid;
else l = mid+1;
}
cout<<l<<"\n";
}
