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#include <bits/stdc++.h>
using namespace std;

#define rep(i, a, b) for (int i = (a); i < (b); i++)
#define all(x) begin(x), end(x)
#define sz(x) int((x).size())
using ll = long long;
using pii = pair<int, int>;
using vi = vector<int>;

#ifdef LOCAL
auto operator<<(auto& o, auto x) -> decltype(x.first, o);
auto operator<<(auto& o, auto x) -> decltype(x.end(), o) {
  o << "{";
  for (int i = 0; auto y : x) o << ", " + !i++ * 2 << y;
  return o << "}"; }
auto operator<<(auto& o, auto x) -> decltype(x.first, o) {
  return o << "(" << x.first << ", " << x.second << ")"; }
void __print(auto... x) { ((cerr << x << " "), ...) << endl; }
#define debug(x...) __print("[" #x "]:", x)
#else
#define debug(...) 2137
#endif

const int N = 1010;
const ll INF64 = 2e18;
int n;
ll k;
int a[N];

ll licz(vector<ll> v) {
  ll odp = 0;
  rep(i, 1, sz(v)) {
    vector<ll> dod(i + 1);
    ll tu = max(0ll, v[i] - (v[i - 1] + k));
    debug(i, v, tu);
    for (int j = i - 1; j > 0; j--) {
      if (v[j] < v[j - 1] + k) {
        ll wez = min(v[j - 1] + k - v[j], tu);
        tu -= wez;
        dod[j] += wez;
        debug(j, wez);
      }
    }
    rep(j, 1, i) {
      dod[j] += dod[j - 1];
      odp += dod[j];
      v[j] += dod[j];
    }
    assert(v[i] <= v[i - 1] + k);
    if (v[i] < v[i - 1] - k) {
      odp += v[i - 1] - k - v[i];
      v[i] = v[i - 1] - k;
    }
  }
  return odp;
}

int main() {
  cin.tie(0)->sync_with_stdio(0);
  cin >> n >> k;
  rep(i, 0, n) cin >> a[i];
  int m = max_element(a, a + n) - a;
  vector<ll> lew(a, a + m + 1);
  reverse(all(lew));
  vector<ll> pra(a + m, a + n);
  cout << licz(lew) + licz(pra) << '\n';
}