///
/// Oh? You're approaching me?
///
#include <bits/stdc++.h>
#define Loop(x,l,r) for(ll x = ll(l); x < ll(r); ++x)
#define LoopR(x,l,r) for(ll x = ll(r)-1; x >= ll(l); --x)
#define Kill(x) exit((cout << (x) << '\n', 0))
typedef long long ll;
typedef std::pair<int,int> pii;
typedef std::pair<ll,ll> pll;
using namespace std;
const int N = 2010;
int dp[N][N];
int a[N];
int n, p, q;
void solve(int w){
int p1=0, p2=0;
Loop(i,0,n){
while(a[i]-a[p1] >= w) ++p1;
while(a[i]-a[p2] >= 2*w) ++p2;
dp[i+1][0] = dp[p1][0]+1;
Loop(k,1,q+1) dp[i+1][k] = min(dp[p1][k]+1, dp[p2][k-1]);
}
}
int main()
{
cin.tie(0) -> sync_with_stdio(false);
cin >> n >> p >> q;
Loop(i,0,n) cin >> a[i];
if(q>=n) Kill(1);
sort(a,a+n);
int l=1, r=1e9;
while(l<r){
int m = (l+r)/2;
solve(m);
if(dp[n][q] <= p) r=m;
else l=m+1;
}
cout << l << '\n';
}
