#include <bits/stdc++.h>
using namespace std;
template<typename A, typename B> ostream& operator<<(ostream &os, const pair<A, B> &p) { return os << '(' << p.first << ", " << p.second << ')'; }
template<typename T_container, typename T = typename enable_if<!is_same<T_container, string>::value, typename T_container::value_type>::type> ostream& operator<<(ostream &os, const T_container &v) { os << '{'; string sep; for (const T &x : v) os << sep << x, sep = ", "; return os << '}'; }
#define ll long long
#define ld long double
#define all(a) (a).begin(), (a).end()
#define sui cout.tie(NULL); cin.tie(NULL); ios_base::sync_with_stdio(false)
const int MAX_N = 1e5 + 5;
const int MOD = 1e9 + 7;
const ll INF = 1e9;
const ld EPS = 1e-9;
const int LOG = 30;
int n, k, t;
int a[MAX_N];
bool check(int s)
{
bool dp[n + 1][n + 1];
dp[k][k] = true;
for (int i = k; i >= 0; i--)
{
for (int j = (i == k ? k + 1 : k); j < n; j++)
{
dp[i][j] = false;
if (a[j] - a[i] <= 1ll * (j - i) * s * t * 2) dp[i][j] = (i < k ? dp[i + 1][j] : false) || (j > k ? dp[i][j - 1] : false);
}
}
return dp[0][n - 1];
}
void solve() {
cin >> n >> k >> t;
k--;
for (int i = 0; i < n; i++) cin >> a[i];
int l = -1;
int r = 1e9;
while (r - l > 1)
{
int mid = (r + l) >> 1;
if (check(mid)) r = mid;
else l = mid;
}
cout << r << "\n";
}
int main() {
sui;
int tc = 1;
//cin >> tc;
for (int t = 1; t <= tc; t++) {
solve();
}
}
