#include <bits/stdc++.h>
using namespace std;
int n,sm,bg,a[2001];
int dp[2001][2001];
bool check(int w) {
for (int i=0; i<n; ++i) {
int preb=(int)(upper_bound(a,a+n,a[i]-2*w)-a)-1;
int pres=(int)(upper_bound(a,a+n,a[i]-w)-a)-1;
if (pres!=-1) dp[i][0]=dp[pres][0]+1;
else dp[i][0]=1;
for (int j=1; j<=bg; ++j) {
if (preb==-1) dp[i][j]=0;
else dp[i][j]=min(dp[preb][j-1],dp[pres][j]+1);
}
}
if (dp[n-1][bg]<=sm) return true;
else return false;
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin>>n>>sm>>bg;
for (int i=0; i<n; ++i) cin>>a[i];
sort(a,a+n);
if (sm+bg>=n) {
cout<<1;
return 0;
}
int l=1,r=1e9,ans=1e9;
while (l<=r) {
int mid=(l+r)/2;
if (check(mid)) ans=mid,r=mid-1;
else l=mid+1;
}
cout<<ans;
}
