//	Totally unrelated and not AT ALL stolen from hohohaha's template
#include <bits/stdc++.h>
using namespace std;
#define arctan atan
#define arccos acos
#define arcsin asin
#define mp make_pair
#define pb push_back
#define eb emplace_back
#define fi first
#define se second
#define lb lower_bound
#define ub upper_bound
#define vt vector
#define pr pair
#define all(a) (a).begin(),(a).end()
#define Ahhhhhhhh		 "It's_ca_khia_Tham_:))"	// Rewind 2018 reference
#define Le_Minh_Tam		 "xinh"// though, a define is not needed.
#define Hoang_Duong		 "AC_10e69+7_bai_A_in_orz_minutes"
#define Andy_Duke_Anh	 "*Fantasie_Impromptu_100*"
#define Le_Phuc_Vinh	 "*T_dang_dung_check-pat*"
#define Kat_Bongo 		 "***Best_Python_Sniper***"
#define Chau_Vu	  		 "**SupaKHUNG_va_hoicham**"	// also very god of dp (yes, you read that right)
#define ZaP_zU	  		 "***Sieu_khung_va_orz***"	// also Asian tourist
#define Grey_rabbit		 "****Khung_ko_kem_ai****"
#define Pham_Hoang_Hiep	 "a.k.a_LuuNgocThaiSon-orz"
#define DTNhat_Long		 "***Bacc-tracc-ing_God***"
#define Nguyen_Nhat_Minh "**khungkhungkhungkhung**"	// I mean, there's not
#define Pham_Truong_Dat	 "orz_orz_ORZ!!!!!!!!!!!!!"	// much to say about
#define Duong_Minh_Khoi  "****don_thuan_la_ORZ****"	// these three people
#define Ta_Xuan_Duy  	 "*sieudepzainhungkokhung*"
#define Hachi_Minh		 "..." // yes, I haven't thought of one yet.  "F"s in the chat bois.
#define Lan_Leeeeee		 "Lan_le_bo_toai,_get_it??" // No? Ok fine that was smol pp joke on my part.
#define Chui_Minh_Hiu	 "Game_it_thoi"
#define endl			 "\n"
//	Disscliamer:  	- I do not know how to spell "Disclaimer" (thanks google for the correct spelling)
//					- Also, as stated by no laws that I can tell, the previous sentences are written for
//					the sake of "ca_khia"-ing. To the people mentioned in these sentences, the sentences
//					may not represent you as a person (though I do think that I'm pretty handsome myself)
//					and should not be taken as neither the truth, nor a personal attacc. Pls, no bulli.
//	Can't belive I spent 20+ lines and 6+ hours to do this. Oh well,
//	Until next time, remember:
//			You are closer, than you think.
typedef double db;         typedef long long li;        typedef long double ld;	         typedef string str;
typedef pr<int, int> ii;   typedef pr<li,li> ll;        typedef pr<ld,ld> dd;
typedef vt<int> vi;        typedef vt<li> vli;          typedef vt<bool> vb;
typedef vt<str> vs;        typedef vt<ii> vii;          typedef vt<ll> vll;
typedef map<int, int> mii; typedef map<int, bool> mib;  typedef map<int, str> mis;       typedef map<int, char> mic;
typedef set<int> s_i;      typedef set<char> s_c;       typedef set<str> s_s;
typedef complex<db> cpx;  typedef vt<cpx> vcpx;
const int mod = 1e9+7;     const li inf = 1e18;
#define pi 3.141592653589793
#define int li
//	ios_base::sync_with_stdio(0), cin.tie(0), cout.tie(0);
mii met;

signed main()
{
	int n; cin >> n;
	int a[n+2];
	for(int i = 0; i < n; ++i)
	{
		cin >> a[i]; ++met[a[i]];
	}
	int ans = 0;
	for(int i = 0; i < n; ++i)
	{
		if (met[a[i]] > a[i])
		{
			ans += met[a[i]] - a[i];
			met[a[i]] = 0;
		}
		else if (met[a[i]] < a[i])
		{
			ans += met[a[i]];
			met[a[i]] = 0;
		}
	}
	cout << ans;
}
// with the aura of Dora, AC!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!!1!!!!!!!!!!!!!!!!!
// 	Why is there a one in my row of exclamation marks?

Measured memory_bytes: 5504