# include <bits/stdc++.h>
using namespace std;
#define int long long
int n,p,q,a[2005],dp[2005][100005];
bool check(int w)
{
for (int i =0; i <= n; i++)
{
for (int j = 0; j <= q; j++)
{
dp[i][j] = n+1;
}
}
dp[0][0] = 0;
int j = 1, k = 1;
for (int i = 1; i <= n; i++)
{
while (j <= i and a[i]-a[j]+1 > w)
{
j++;
}
while (k <= i and a[i]-a[k]+1 > w*2)
{
k++;
}
for (int t = 0; t <= p; t++)
{
if (t > 0) dp[i][t] = min(dp[i][t],dp[j-1][t-1]);
dp[i][t] = min(dp[i][t],dp[k-1][t]+1);
}
}
bool checky = false;
for (int i = 0; i <= p; i++)
{
// cerr << dp[n][i] << " ";
if (dp[n][i] <= q) checky = true;
}
return checky;
}
int bs()
{
int l = 1, r = a[n], mid;
while (l <= r )
{
mid = (l+r)/2;
if (check(mid)) r = mid-1;
else l = mid+1;
}
return l;
}
signed main()
{
ios_base::sync_with_stdio(false);
cin.tie(0);
cin >> n >> p >> q;
for (int i = 1; i <= n; i++)
{
cin >> a[i];
}
sort(a+1,a+n+1);
cout << bs();
// cout << check(3);
}
