#include<bits/stdc++.h>
using namespace std;
// JANGAN LUPA CEK PERLU LL NGGAK
#define pb push_back
#define pii pair<int,int>
#define fi first
#define inf INT_MAX
#define se second
#define miku ios_base::sync_with_stdio(0);cin.tie(0);cout.tie(0);
vector<int>a;
signed main(){
miku
int n,p,q;cin>>n>>p>>q;
q=min(n,q);
a.assign(n+1,0);
for(int i=1;i<=n;i++)cin>>a[i];
sort(a.begin()+1,a.end());
int l=1,r=a[n]-a[1]+1;
int ans=0;
while(l<=r){
int mid=(l+r)/2;
int j=1;
int mini=inf;
int dp[n+10][q+10];
memset(dp,0,sizeof(dp));
int deketk=1,deket2k=1;
for(int i=1;i<=n;i++){
while(a[i]-a[deketk]+1>mid)deketk++;
while(a[i]-a[deket2k]+1>2*mid)deket2k++;
dp[i][0]=dp[deketk-1][0]+1;
for(int j=1;j<=q;j++){
dp[i][j]=dp[deket2k-1][j-1];
dp[i][j]=min(dp[deketk-1][j]+1,dp[i][j]);
// if(mid==2) cout<<i<<" "<<j<<" "<<dp[binser(i,2*mid)-1][j-1]<<" "<<dp[binser(i,2*mid)-1][j-1]<<endl;
}
}
for(int i=0;i<=q;i++) mini=min(mini,dp[n][i]);
// cout<<mid<<' '<<mini<<endl;
if(mini<=p){
r=mid-1;
ans=mid;
}
else l=mid+1;
}
cout<<ans;
}
