#include <bits/stdc++.h>
#define ll long long
#define sp << " "
#define faster ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0)
using namespace std;
ll n, p, q, a[2005], dp[2005][2005], k, l;
bool check(ll mid){
memset(dp,63,sizeof(dp));
dp[0][0]=0;
k=1,l=1;
for(ll i = 1; i <= n; i++){
while(a[i]-a[k]+1>mid) k++;
while(a[i]-a[l]+1>2*mid) l++;
for(ll j = 0; j <= q; j++){
dp[i][j]=dp[k-1][j]+1;
if(j>0) dp[i][j]=min(dp[i][j],dp[l-1][j-1]);
}
}
for(ll i = 0; i <= q; i++) if(dp[n][i]<=p) return true;
return false;
}
int main(){
faster;
cin >> n >> p >> q;
for(ll i = 1; i <= n; i++) cin >> a[i];
sort(a+1,a+n+1);
if(p>=n||q>=n){
cout << 1;
return 0;
}
ll l = 1, r = 1e15, mid;
while(l<=r){
mid=(l+r)/2;
if(!check(mid)) l=mid+1;
else r=mid-1;
}
cout << l;
return 0;
}
