#include <bits/stdc++.h>
using namespace std;
long long int gcd(long long int a, long long int b) {
  if (!b) return a;
  return gcd(b, a % b);
}
long long int power(long long int x, long long int y, long long int p) {
  long long int res = 1;
  x %= p;
  while (y > 0) {
    if (y & 1) res = (res * x) % p;
    y = y >> 1;
    x = (x * x) % p;
  }
  return res;
}
long long int lcm(long long int a, long long int b) {
  return (a * b) / gcd(a, b);
}
long long int searchll(long long int val, vector<long long int> vec) {
  for (long long int i = 0; i < vec.size() - 1; i++) {
    if (vec[i] == val) {
      return i;
    }
  }
  return -1;
}
bool isPrime(long long int n) {
  int broken = 0;
  for (long long int i = 2; i < sqrt(n); i++) {
    if (n % i == 0) {
      broken = 1;
      break;
    }
  }
  if (broken == 1) {
    return false;
  } else {
    return true;
  }
}
bool isPerfectSquare(long double x) {
  long double sr = sqrt(x);
  return ((sr - floor(sr)) == 0);
}
vector<bool> SieveOfEratosthenes(long long int num) {
  vector<bool> pno;
  pno.assign(num + 1, true);
  pno[0] = false;
  pno[1] = false;
  for (long long int i = 2; i * i <= num; i++) {
    if (pno[i] == true) {
      for (long long int j = i * 2; j <= num; j += i) pno[j] = false;
    }
  }
  return pno;
}
void solve() {
  long long int n;
  cin >> n;
  vector<long long int> weights;
  for (long long int i = 0; i < n; i++) {
    long long int x;
    cin >> x;
    weights.push_back(x);
  }
  sort(weights.begin(), weights.end());
  long long int stacks = 0;
  long long int remSize = 0;
  long long int start;
  int broken = 0;
  long long int used = 0;
  long long int ans = 0;
  while (used < n) {
    long long int h = 0;
    ans++;
    for (long long int i = 0; i < n; i++) {
      if (weights[i] >= h) {
        weights[i] = -1;
        used++;
        h++;
      }
    }
  }
  cout << ans << "\n";
}
signed main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  solve();
}
