#include <bits/stdc++.h>
using namespace std;
#pragma GCC target("avx2")
#pragma GCC optimization("unroll-loops")
#pragma GCC optimize("O2")
constexpr int dx[] = {-1, 0, 1, 0, 1, 1, -1, -1};
constexpr int dy[] = {0, -1, 0, 1, 1, -1, 1, -1};
constexpr long long INF = 1999999999999999997;
constexpr int inf = INT_MAX;
constexpr int MAXSIZE = int(1e6) + 5;
constexpr auto PI = 3.14159265358979323846L;
constexpr auto oo = numeric_limits<int>::max() / 2 - 2;
constexpr auto eps = 1e-6;
constexpr auto mod = 1000000007;
constexpr auto MOD = 1000000007;
constexpr auto MOD9 = 1000000009;
constexpr auto maxn = 100006;
void fastio() {
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
}
long long height[200005];
int main() {
  fastio();
  long long n, k;
  cin >> n >> k;
  long long a[n];
  long long mini = INT_MAX;
  for (int i = 0; i < n; i++) {
    cin >> a[i];
    height[a[i]]++;
    mini = min(mini, a[i]);
  }
  sort(a, a + n);
  bool ok = a[0] != a[n - 1];
  for (int i = 200002; i >= 0; i--) {
    height[i] += height[i + 1];
  }
  int ans = ok;
  long long curr = 0;
  for (int i = 200002; i > mini; i--) {
    if (height[i] + curr > k) {
      ans++;
      curr = 0;
    }
    curr += height[i];
  }
  cout << ans;
}
