#include<bits/stdc++.h>
using namespace std;
using intt=int32_t;
#define debug(n,m) cout<<"["<<#n<<"]->"<<n<<m
#define int long long
#define all(x) x.begin(),x.end()
#define pb push_back
const int N=10001;
const int mod=1e9;
const int inf=2e9;
int n,p,q;
int a[N];
bool check(int x){
vector<vector<int>> dp(n+1,vector<int>(p+1,inf));
vector<int> sm(n+1,0);
vector<int> la(n+1,0);
for (int i=0;i<n;++i) {
sm[i]=upper_bound(a+1,a+n+1,a[i+1]+x-1)-a-1;
la[i]=upper_bound(a+1,a+n+1,a[i+1]+2*x-1)-a-1;
}
dp[0][0]=0;
for (int i=0;i<n;++i) {
for (int j=0;j<=p;++j) {
if(j<p)dp[sm[i]][j+1]=min(dp[sm[i]][j+1],dp[i][j]);
dp[la[i]][j]=min(dp[la[i]][j],dp[i][j]+1);
}
}
int fl=0;
for (int j=0;j<=p;++j) if (dp[n][j]<=q) fl=1;
return fl;
}
void levi() {
cin>>n>>p>>q;
a[0]=1;
for (int i=1;i<=n;++i) cin>>a[i];
sort(a+1,a+n+1);
if (p+q>=n) {
cout<<1<<'\n';
return;
}
int lo=1,hi=1e9;
int res=1e9;
while(lo<=hi) {
int mid=lo+(hi-lo)/2;
if (check(mid)) {
res=mid;
hi=mid-1;
}
else lo=mid+1;
}
cout<<res<<'\n';
}
int32_t main() {
ios_base::sync_with_stdio(0);
cin.tie(0);int tt=1;//cin>>tt;
while(tt--)levi();
}
