#include <bits/stdc++.h>
using namespace std;
const long long dx[4] = {-1, 1, 0, 0};
const long long dy[4] = {0, 0, -1, 1};
long long XX[] = {-1, -1, -1, 0, 0, 1, 1, 1};
long long YY[] = {-1, 0, 1, -1, 1, -1, 0, 1};
const long long N = (long long)(6 * 1e5 + 10);
const long long M = 1e9 + 7;
long long fact[N], invfact[N];
long long pow(long long a, long long b, long long m) {
  long long ans = 1;
  while (b) {
    if (b & 1) ans = (ans * a) % m;
    b /= 2;
    a = (a * a) % m;
  }
  return ans;
}
long long modinv(long long k) {
  return pow(k, (long long)998244353 - 2, (long long)998244353);
}
void precompute() {
  fact[0] = fact[1] = 1;
  for (long long i = 2; i < N; i++)
    fact[i] = fact[i - 1] * i, fact[i] %= (long long)998244353;
  invfact[N - 1] = modinv(fact[N - 1]);
  for (long long i = N - 2; i >= 0; i--)
    invfact[i] = invfact[i + 1] * (i + 1), invfact[i] %= (long long)998244353;
}
long long nCr(long long x, long long y) {
  if (y > x) return 0;
  long long num = fact[x];
  num *= invfact[y];
  num %= (long long)998244353;
  num *= invfact[x - y];
  num %= (long long)998244353;
  return num;
}
int32_t main() {
  ;
  ios_base::sync_with_stdio(false);
  cin.tie(NULL);
  cout.tie(NULL);
  ;
  long long n, i;
  long long a[1010];
  cin >> n;
  for (i = 0; i < n; i++) cin >> a[i];
  sort(a, a + n);
  long long ans = 0;
  long long x;
  for (i = 0; i < n; i++) {
    x = 0;
    if (a[i] != -1) {
      ans++;
      x++;
      a[i] = -1;
      for (long long j = i + 1; j < n; j++) {
        if (a[j] != -1 && a[j] >= x) {
          a[j] = -1;
          x++;
        }
      }
    }
  }
  cout << ans << endl;
  return 0;
}
