哪位好人来救救孩子……

# include <bits/stdc++.h>
# define int long long
# define endl '\n'
# define str string
# define fst ios::sync_with_stdio (0); cin.tie (0); cout.tie (0);

using namespace std;

const int N = 1e6 + 5, M = 2e6 + 5;
const int P = 1e9 + 7;
const int INF = 0x3f3f3f3f;
const int LNF = 0x3f3f3f3f3f3f3f3f;

int n, k;
int a[N];
int maxn;
int l, r, mid;
int ans;

bool check (int x) {
	if (! x) {
		return 1;
	} 
	int cnt = 0;
	int sum = 0;
	int j = 1;
	int use;
	for (int i = 1; i <= x; i ++ ) {
		while ((j <= n) && (a[j] <= i)) {
			sum += a[j];
			cnt ++;
			j ++;
		}
		use = (((cnt * (i + 1))) - sum);
		if (use > (i * k)) {
			return 0;
		}
	}
	return 1;
}

signed main () {
	fst;
	cin >> n >> k;
	for (int i = 1; i <= n; i ++ ) {
		cin >> a[i];
		maxn = max (maxn, a[i]);
	}
	sort (a + 1, a + 1 + n);
	r = (maxn + maxn + n);
	while (l <= r) {
		mid = ((l + r) / 2);
		if (check (mid)) {
			ans = mid;
			l = (mid + 1);
		}
		else {
			r = (mid - 1);
		}
	}
	cout << ans;
	return 0;
}