#include<bits/stdc++.h>
using namespace std;
#define all(x) (x).begin(), (x).end()
#define sz(x) ( (int)(x).size() )
using LL = long long;
template<class T>
inline bool asMn(T &a, const T &b) { return a > b ? a = b, true : false; }
template<class T>
inline bool asMx(T &a, const T &b) { return a < b ? a = b, true : false; }
mt19937 rng( (uint32_t)chrono::steady_clock::now().time_since_epoch().count() );
int n, k, t;
vector<int> x;
bool check(int s) {
vector<vector<bool> > f(n, vector<bool>(n, false) );
f[k][k] = true;
for (int diff = 0; diff < n; ++diff) {
for (int i = 0, j = diff; j < n; ++i, ++j) if (f[i][j]) {
if (i && (x[j] - x[i - 1] + t - 1) / t <= 2LL * s * (j - i + 1) ) f[i - 1][j] = true;
if (j + 1 < n && (x[j + 1] - x[i] + t - 1) / t <= 2LL * s * (j - i + 1) ) f[i][j + 1] = true;
}
}
return f[0][n - 1];
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
#ifdef FourLeafClover
freopen("input", "r", stdin);
#endif // FourLeafCLover
cin >> n >> k >> t; --k;
x.assign(n, 0);
for (auto &i : x) cin >> i;
int l = 0, r = x.back();
while (l < r) {
int mid = (l + r) >> 1;
if (check(mid) ) r = mid;
else l = mid + 1;
}
cout << l << '\n';
return 0;
}
