using System;
using System.Linq;
using System.Collections.Generic;

namespace Contest
{
    class Program
    {
        static void Main(string[] args)
        {
            ARC087.C();
        }
        class ARC087
        {
            public static void C()
            {
                var N = Read.Int();
                var A = Read.IntN();
                var freq = Util.Frequency(A);
                int count = 0;
                foreach(var kvp in freq)
                {
                    var k = kvp.Key;
                    var v = (int)kvp.Value;
                    if (k <= v)
                    {
                        count += v - k;
                    }
                    else
                    {
                        count += v;
                    }
                }
                Console.WriteLine(count);
            }
            public static void D()
            {
                var S = Read.Str();
                var X = Read.Int();
                var Y = Read.Int();
                var counts = S.Split('T').Select(x => x.Length).ToArray();
                var LX = new List<int>();
                var LY = new List<int>();
                for(int i = 1; i < counts.Length; ++i)
                {
                    (i % 2 == 0 ? LX : LY).Add(counts[i]);
                }
                Console.WriteLine(D_CanMake(LX, X - counts[0]) && D_CanMake(LY, Y) ? "Yes" : "No");
            }
            static bool D_CanMake(List<int> list, int value)
            {
                list = list.Where(x => x > 0).OrderBy(x => x).ToList();
                var sum = list.Sum();
                var dp = Enumerable.Range(0, list.Count + 1).Select(i => new HashSet<int>()).ToArray();
                dp[0].Add(0);
                for(int i = 0; i < list.Count; ++i)
                {
                    var v = list[i];
                    var h = dp[i + 1];
                    foreach(var w in dp[i])
                    {
                        if (!h.Contains(w + v)) { h.Add(w + v); }
                        if (!h.Contains(w - v)) { h.Add(w - v); }
                    }
                }
                return dp[list.Count].Contains(value);
            }
        }

        class Util
        {
            public static Dictionary<T, long> Frequency<T>(T[] array)
            {
                var dict = new Dictionary<T, long>();
                foreach (var a in array)
                {
                    if (!dict.ContainsKey(a)) { dict.Add(a, 0); }
                    dict[a]++;
                }
                return dict;
            }
        }

        static class Read
        {
            static Queue<string> queue = new Queue<string>();
            static void Enqueue() { var ss = Console.ReadLine().Split(' '); foreach (var s in ss) { queue.Enqueue(s); } }
            public static int Int() { if (queue.Count == 0) { Enqueue(); } return Convert.ToInt32(queue.Dequeue()); }
            public static long Long() { if (queue.Count == 0) { Enqueue(); } return Convert.ToInt64(queue.Dequeue()); }
            public static string Str() { if (queue.Count == 0) { Enqueue(); } return queue.Dequeue(); }
            public static int[] IntN() { return Console.ReadLine().Split(' ').Select(s => Convert.ToInt32(s)).ToArray(); }
            public static long[] LongN() { return Console.ReadLine().Split(' ').Select(s => Convert.ToInt64(s)).ToArray(); }
            public static string[] StrN() { return Console.ReadLine().Split(' '); }
            public static Tuple<int, int>[] TupleInt(int n) { List<Tuple<int, int>> list = new List<Tuple<int, int>>(); for (int i = 0; i < n; ++i) { var ab = Read.IntN(); list.Add(new Tuple<int, int>(ab[0], ab[1])); } return list.ToArray(); }
            public static Tuple<long, long>[] TupleLong(int n) { List<Tuple<long, long>> list = new List<Tuple<long, long>>(); for (int i = 0; i < n; ++i) { var ab = Read.LongN(); list.Add(new Tuple<long, long>(ab[0], ab[1])); } return list.ToArray(); }
            public static Tuple<string, string>[] TupleStr(int n) { List<Tuple<string, string>> list = new List<Tuple<string, string>>(); for (int i = 0; i < n; ++i) { var ab = Read.StrN(); list.Add(new Tuple<string, string>(ab[0], ab[1])); } return list.ToArray(); }
            public static Tuple<double, double>[] TupleDouble(int n) { List<Tuple<double, double>> list = new List<Tuple<double, double>>(); for (int i = 0; i < n; ++i) { var ab = Read.LongN(); list.Add(new Tuple<double, double>(ab[0], ab[1])); } return list.ToArray(); }
            public static long[,] LongMatrix(int r, int c)
            {
                var mat = new long[r, c];
                for (int i = 0; i < r; ++i)
                {
                    var x = Read.LongN();
                    for (int j = 0; j < c; ++j)
                    {
                        mat[i, j] = x[j];
                    }
                }
                return mat;
            }
            public static Dictionary<int, HashSet<int>> AdjacencyList(int N, int M, bool isDirectional = false)
            {
                Dictionary<int, HashSet<int>> dict = new Dictionary<int, HashSet<int>>();
                for (int i = 0; i <= N; ++i) { dict.Add(i, new HashSet<int>()); }
                for (int i = 0; i < M; ++i)
                {
                    var ab = Read.IntN(); dict[ab[0]].Add(ab[1]);
                    if (!isDirectional) { dict[ab[1]].Add(ab[0]); }
                }
                return dict;
            }
            public static Dictionary<int, Dictionary<int, long>> AdjacencyListWithWeight(int N, int M)
            {
                Dictionary<int, Dictionary<int, long>> dict = new Dictionary<int, Dictionary<int, long>>();
                for (int i = 0; i <= N; ++i)
                {
                    dict.Add(i, new Dictionary<int, long>());
                }
                for (int i = 0; i < M; ++i)
                {
                    var ab = Read.IntN();
                    dict[ab[0]].Add(ab[1], ab[2]);
                    dict[ab[1]].Add(ab[0], ab[2]);
                }
                return dict;
            }
        }
    }
}


Measured memory_bytes: 29920