#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
#include <bits/stdc++.h>
#include <ext/pb_ds/tree_policy.hpp>
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/rope>
using namespace std;
using namespace __gnu_pbds;
using namespace __gnu_cxx;
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;
typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;
typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;
template <class T> using Tree = tree<T, null_type, less<T>, rb_tree_tag,tree_order_statistics_node_update>;
#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
const int MOD = 1000000007;
const ll INF = 1e18;
const int MX = 100001;
int N,K,T,mid;
vi X;
bool ok[1000][1000][2];
// k = 0:
// X[i-1]+t*mid
// currently at X[i]+t*mid
// X[j]-t*mid
// X[j+1]-t*mid
bool OK() {
F0Rd(i,K+1) FOR(j,K,N) F0R(k,2) ok[i][j][k] = 0;
ok[K][K][0] = ok[K][K][1] = 1;
F0Rd(i,K+1) FOR(j,K,N) {
ld dis = (ld)(j-i+1)*T*2*mid;
if (dis >= X[j]-X[i]) {
ok[i][j][0] |= ok[i][j][1];
ok[i][j][1] |= ok[i][j][0];
}
if (i && dis >= X[j]-X[i-1]) ok[i-1][j][0] |= ok[i][j][0];
if (j < N-1 && dis >= X[j+1]-X[i]) ok[i][j+1][1] |= ok[i][j][1];
}
return ok[0][N-1][0] || ok[0][N-1][1];
}
int main() {
ios_base::sync_with_stdio(0); cin.tie(0);
cin >> N >> K >> T; X.resize(N); K--;
F0R(i,N) cin >> X[i];
int lo = 0, hi = 1000000000;
while (lo < hi) {
mid = (lo+hi)/2;
if (OK()) hi = mid;
else lo = mid+1;
}
cout << lo;
}
/* Look for:
* the exact constraints (multiple sets are too slow for n=10^6 :( )
* special cases (n=1?)
* overflow (ll vs int?)
* array bounds
* if you have no idea just guess the appropriate well-known algo instead of doing nothing :/
*/
