#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int MAXN = 2010;
vector<ll> V;
ll dp[MAXN][MAXN],nxt[MAXN][2],N,P,Q,W;
ll solve(ll pos,ll resta){
if(dp[pos][resta] != -1) return dp[pos][resta];
if(pos == N) return 0;
ll best = 1 + solve(nxt[pos][0]+1,resta);
if(resta != 0) best = min(best, solve(nxt[pos][1] + 1,resta - 1) );
return dp[pos][resta] = best;
}
ll check(ll val){
W = val;
memset(dp,-1,sizeof(dp));
for(ll i = 0;i<N;i++){
nxt[i][0] = prev(upper_bound(V.begin(),V.end(),V[i] + W - 1)) - V.begin();
nxt[i][1] = prev(upper_bound(V.begin(),V.end(),V[i] + 2*W - 1)) - V.begin();
}
return solve(0,Q) <= P;
}
int main(){
cin >> N >> P >> Q;
for(ll i = 0;i<N;i++){
ll x;
cin >> x;
V.push_back(x);
}
sort(V.begin(),V.end());
V.erase(unique(V.begin(),V.end()),V.end());
N = V.size();
P = min(P,N);
Q = min(Q,N);
ll ini = 1,fim = (ll)1e9,meio,resp = -1;
while(ini <= fim){
meio = ini + (fim - ini)/2;
if(check(meio)){
resp = meio;
fim = meio - 1;
}
else{
ini = meio + 1;
}
}
cout << resp << endl;
return 0;
}
