// vaziat meshki-ghermeze !
#include <bits/stdc++.h>
#define pb push_back
#define F first
#define S second
#define all(x) x.begin(), x.end()
#define debug(x) cerr << #x << " : " << x << '\n'
using namespace std;
typedef long long ll;
typedef long double ld;
typedef string str;
typedef pair<ll, ll> pll;
const ll Mod = 1000000007LL;
const int N = 2e3 + 10;
const ll Inf = 2242545357980376863LL;
const ll Log = 30;
int n, k;
ll X[N];
vector<ll> A, B;
ll psA[N], psB[N];
int dp[N][N];
bool Check(ll T){
if(T > 1000000000)
return true;
A = {T};
B = {};
for(int i = k + 1; i <= n; i++){
A.pb(X[i - 1] - X[i]);
A.pb(T);
}
for(int i = k - 1; i >= 1; i--){
B.pb(X[i] - X[i + 1]);
B.pb(T);
}
psA[0] = 0;
for(int i = 1; i <= (int) A.size(); i++)
psA[i] = psA[i - 1] + A[i - 1];
psB[0] = 0;
for(int i = 1; i <= (int) B.size(); i++)
psB[i] = psB[i - 1] + B[i - 1];
memset(dp, 0, sizeof dp);
int sa = A.size(), sb = B.size();
int pa = 0, pb = 0;
while((pa < sa) || (pb < sb)){
ll nw = psA[pa] + psB[pb];
if(nw < 0) return false;
if(pa == sa){
if(psA[pa] + psB[pb + 1] < 0) return false;
pb ++;
continue;
}
if(pa == sa){
if(psA[pa] + psB[pb + 1] < 0) return false;
pb ++;
continue;
}
int des = pa;
for(int nx = pa + 1; nx <= sa; nx ++){
if(psA[nx] + psB[pb] < 0) break;
if(psA[pa] <= psA[nx]){
des = nx;
break;
}
}
if(des > pa){
pa = des;
continue;
}
des = pb;
for(int nx = pb + 1; nx <= sb; nx ++){
if(psA[pa] + psB[nx] < 0) break;
if(psB[pb] <= psB[nx]){
des = nx;
break;
}
}
if(des > pb){
pb = des;
continue;
}
pa ++;
}
return psA[sa] + psB[sb] >= 0;
}
int main(){
ios::sync_with_stdio(0); cin.tie(0); cout.tie(0);
ll T;
cin >> n >> k >> T;
for(int i = 1; i <= n; i++)
cin >> X[i];
int mid, L = -1, R = 1000000000;
while(L + 1 < R){
mid = (L + R) >> 1;
if(Check(2ll * T * mid))
R = mid;
else L = mid;
}
cout << R << '\n';
return 0;
}
