#include <bits/stdc++.h>
#define int long long
using namespace std;
int l[1000006], r[1000006], a[1000006], n, top, cnt[1000006], ans[1000006], k, ll[1000006], rr[1000006];
stack<int> s;
inline void update(int p) {
	int lst = 0;
	while (s.size()) {
		if (a[p] < a[s.top()]) {
			lst = s.top();
			s.pop();
			continue;
		} else {
			l[p] = lst;
			r[s.top()] = p;
			s.push(p);
			return;
		}
	}
	l[p] = lst;
	top = p;
	s.push(p);
}
inline void dfs(int p, int q) {
	ll[p] = p;
	rr[p] = p;
	if (l[p]) {
		dfs(l[p], p);
		ll[p] = ll[l[p]];
	}
	if (r[p]) {
		dfs(r[p], p);
		rr[p] = rr[r[p]];
	}
}
inline void ddfs(int p, int q) {
	int op = (a[p] - a[q]) * (rr[p] - ll[p] + 1);
	if (l[p]) ddfs(l[p], p), ans[p] += ans[l[p]], cnt[p] += cnt[l[p]];
	if (r[p]) ddfs(r[p], p), ans[p] += ans[r[p]], cnt[p] += cnt[r[p]];
	cnt[p] -= op;
	if (cnt[p] < 0) {
		ans[p] += cnt[p] / (-k) + 1;
		cnt[p] += (cnt[p] / (-k) + 1) * k;
		if (cnt[p] >= k) cnt[p] -= k, ans[p]--;
	}
}
signed main() {
	ios::sync_with_stdio(0);
	cin.tie(0);
	cout.tie(0);
	cin >> n >> k;
	for (int i = 1; i <= n; i++) {
		cin >> a[i];
	}
	s.push(1);
	top = 1;
	for (int i = 2; i <= n; i++) {
		update(i);
	}
	dfs(top, 0);
	ddfs(top, 0);
	cout << ans[top];
}