#include <bits/stdc++.h>
using namespace std;
int n;
vector <int> vect;
vector <int> bigc;
vector <int> smallc;
int dp[2000][100001];
int watching(int index, int small, int w){
if (index>=n){
return 0;
}
if (dp[index][small]!=-1){
return dp[index][small];
}
if (vect[index]+small*w>vect[n-1]){
return 0;
}
if (index==n-1 && small==0){
return 1;
}
int usesmall = INT_MAX, usebig;
usebig = watching(bigc[index], small, w)+1;
if (small>0){
usesmall = watching(smallc[index], small-1, w);
}
dp[index][small] = min(usebig, usesmall);
return dp[index][small];
}
int main(){
int p, q;
cin>>n>>p>>q;
vect.resize(n);
bigc.resize(n);
smallc.resize(n);
for (int i=0; i<n; ++i){
cin>>vect[i];
}
if (p+q>=n){
cout<<1;
return 0;
}
sort(vect.begin(), vect.end());
int low = 0, high = vect[n-1], ans;
while (low+1<high){
for (int i=0; i<n; ++i){
for (int j=0; j<=p; ++j){
dp[i][j] = -1;
}
}
int mid = (low+high)/2;
for (int i=0; i<n; ++i){
smallc[i] = lower_bound(vect.begin(), vect.end(), vect[i]+mid)-vect.begin();
}
for (int i=0; i<n; ++i){
bigc[i] = lower_bound(vect.begin(), vect.end(), vect[i]+mid+mid)-vect.begin();
}
if (watching(0, p, mid)<=q){
ans = mid;
high = mid;
}
else{
low = mid;
}
}
cout<<ans;
}
