#include <bits/stdc++.h>
using namespace std;
using ll = long long;
ll N, K, T, A[100005];
ll D[1005][1005];
void f(ll s, ll e, ll v){
if(s >= 2 && D[s - 1][e] == -1){
if((A[e] - A[s - 1] + 2 * v - 1) / 2 / v <= (e - s + 1) * T){
D[s - 1][e] = 1;
f(s - 1, e, v);
} else {
D[s - 1][e] = 0;
}
}
if(e < N && D[s][e + 1] == -1){
if((A[e + 1] - A[s] + 2 * v - 1) / 2 / v <= (e - s + 1) * T){
D[s][e + 1] = 1;
f(s, e + 1, v);
} else {
D[s][e + 1] = 0;
}
}
}
int main(){
cin.tie(0) -> sync_with_stdio(0);
cin >> N >> K >> T;
for(ll i = 1; i <= N; i++){
cin >> A[i];
}
if(A[N] == 0){
cout << 0; return 0;
}
ll L = 1, R = 1e9;
while(L <= R){
ll m = (L + R) / 2;
fill(D[0], D[1004] + 1005, -1LL);
D[K][K] = 1;
f(K, K, m);
if(D[1][N] == 1) R = m - 1;
else L = m + 1;
}
cout << L;
}
