#include <bits/stdc++.h>
using namespace std;
using ll = long long;
int n, k, t, a[100100], dp[1010][1010];
bool solve(int mid) {
memset(dp, 0, sizeof dp);
dp[k][k] = 1;
for(int l=2;l<=n;l++) {
for(int i=1;i<=n-l+1;i++) {
int j = i+l-1;
if(a[j]-a[i] <= 1ll*(j-i)*t * 2*mid) {
dp[i][j] = dp[i+1][j] | dp[i][j-1];
}
}
}
return dp[1][n];
}
int main() {
cin.tie(0)->sync_with_stdio(0);
cin >> n >> k >> t;
for(int i=1;i<=n;i++) cin >> a[i];
int l = 1, r = 1e9;
while(l <= r) {
int mid = (l+r)/2;
if(solve(mid)) r = mid-1;
else l = mid+1;
}
cout << l;
}
