#include <bits/stdc++.h>
using namespace std;
using ll = long long;
#define MAXN (2005)
ll N,P,Q;
ll arr[MAXN];
bool bs(ll w){
ll dp[N][P + 1]; //number of events covered, number of small cameras, value: number of big cameras needed
memset(dp,0,sizeof(dp));
for(ll i = N - 1;i >= 0;i--){
ll y = lower_bound(arr,arr + N,arr[i] + 2 * w) - arr;
ll x = lower_bound(arr,arr + N,arr[i] + w) - arr;
if (y == N) dp[i][0] = 1;
else dp[i][0] = dp[y][0] + 1;
for(ll j = 1;j <= P;j++) {
if (y == N) dp[i][j] = 1;
else dp[i][j] = dp[y][j] + 1;
if (x == N) dp[i][j] = 0;
else dp[i][j] = min(dp[i][j], dp[x][j - 1]);
}
}
return dp[0][P] <= Q;
}
int main() {
ios_base::sync_with_stdio(false);cin.tie(0);
cin>>N>>P>>Q;
P = min(P,N);
Q = min(Q,N);
for(ll i = 0;i < N;i++){
cin>>arr[i];
}
sort(arr,arr + N);
ll low = 0;
ll high = 1000000000;
while(high - low > 1){
ll mid = (high + low) / 2;
if(bs(mid)){
high = mid;
}else{
low = mid;
}
}
cout<<high<<'\n';
}
