#include <cstdio>
#include <algorithm>
#define maxn 200010
inline int max(int a, int b) {return a > b ? a : b;}
inline int min(int a, int b) {return a < b ? a : b;}

int ans;
int n, M, m = maxn, k, s[maxn];
int v[maxn], pre[maxn], num[maxn];
int main() {
	scanf("%d%d", &n, &k);
	for (int i = 1, x; i <= n; i++) scanf("%d", &x), v[x]++, m = min(m, x), M = max(M, x);
	for (int i = M; i >= m; i--) {
		num[i] = num[i + 1] + v[i];
		pre[i] = pre[i + 1] + num[i];
		if (pre[i] > k) ans++, pre[i] = num[i];
	}
	if (pre[m] > n) ans++;
	printf("%d\n", ans);
	return 0;
}