#include <bits/stdc++.h>
using namespace std;
#define ll long long
ll eve[2003];
ll prv[2003];
ll prvdab[2003];
ll dp[2003][2003];
int main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
ll n,p,q;
cin >> n >> p >> q;
for (ll i = 1; i<=n; i++)cin >> eve[i];
sort(eve+1,eve+n+1);
ll l=1,r=1e9,md;
eve[0]=-1e9;
while(l<r){
md=(l+r)/2;
ll iter=n;
for (ll i = n; i>=1; i--){
while(eve[i]-eve[iter]+1<=md)iter--;
prv[i]=iter;
}
iter=n;
for (ll i = n; i>=1; i--){
while(eve[i]-eve[iter]+1<=2*md)iter--;
prvdab[i]=iter;
}
for (ll i = 1; i<=n; i++){
dp[i][0]=1+dp[prvdab[i]][0];
for (ll j = 1; j<=min(n,p); j++){
dp[i][j]=min(dp[prv[i]][j-1],1+dp[prvdab[i]][j]);
}
}
bool ok=false;
for (ll i = 1; i<=min(n,p); i++)if (dp[n][i]<=q)ok=true;
if (ok)r=md;
else l=md+1;
}
cout << l << '\n';
}
