#include <bits/stdc++.h>
#include <experimental/random>
#include <random>
//#include <ext/pb_ds/assoc_container.hpp>
//using namespace __gnu_pbds;
using namespace std;
using ld = long double;
using ll = long long;
const ll INF = 3e18, MOD = 1e9 + 7;
void solve();
signed main() {
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
ios::sync_with_stdio(false);
cin.tie(0);
int q = 1;
//cin >> q;
while (q--) {
solve();
}
}
void solve() {
ll n, m, k; cin >> n >> m >> k;
vector<ll> a(n + 1);
for (int i = 1; i <= n; i++) cin >> a[i];
vector<ll> dp(n + 1, INF);
dp[0] = 0;
for (int i = 1; i <= n; i++) {
ll mn = INF, mx = -INF, cnt = 0;
for (int l = i; l >= 1; l--) {
if (cnt > m) break;
cnt++, mn = min(mn, a[l]), mx = max(mx, a[l]);
dp[i] = min(dp[i], dp[l - 1] + k + cnt * (mx - mn));
}
}
cout << dp[n];
}
