#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
const int MAXN = 1e3 + 10;
ll n, k, t, x[MAXN];
bool dp[MAXN][MAXN];
vector<ll> h1, h2, h;
void input() {
cin >> n >> k >> t;
--k;
for (int i = 0; i < n; i++)
cin >> x[i];
}
bool check(ll s) {
for (int i = 0; i <= k; i++)
for (int j = k; j < n; j++)
dp[i][j] = false;
dp[k][k] = true;
for (int i = k; i >= 0; i--)
for (int j = k; j < n; j++) {
ll r = (j - i + 1) * s - (x[j] - x[i]);
if (i && r >= x[i] - x[i - 1])
dp[i - 1][j] |= dp[i][j];
if (j < (n - 1) && r >= x[j + 1] - x[j])
dp[i][j + 1] |= dp[i][j];
}
return dp[0][n - 1];
}
ll findAns() {
ll l = -1, r = x[n - 1];
while (r - l > 1) {
ll mid = (l + r) / 2;
if (check(2 * mid * t))
r = mid;
else
l = mid;
}
return r;
}
int main() {
ios::sync_with_stdio(false); cin.tie(0);
input();
if (n == 1)
cout << 0 << endl;
else
cout << findAns() << endl;
return 0;
}
