import std.stdio, std.conv, std.string;
import std.algorithm, std.array, std.container;
import std.numeric, std.math;
import core.bitop;

T RD(T = string)() { static string[] ss; while(!ss.length) ss = readln.chomp.split; string res = ss[0]; ss.popFront; return res.to!T; }
string RDR()() { return readln.chomp; }

long mod = pow(10, 9) + 7;
long moda(long x, long y) { return (x + y) % mod; }
long mods(long x, long y) { return ((x + mod) - (y % mod)) % mod; }
long modm(long x, long y) { return (x * y) % mod; }

void main()
{
	auto N = RD!long;
	auto a = RDR.split.to!(long[]);
	a.sort();

	long ans;
	long last = a[0], lastPos;
	foreach (i; 1..N)
	{
		if (a[i] != last)
		{
			auto x = i - lastPos;
			ans += x >= last ? x - last : x;
			last = a[i];
			lastPos = i;
		}
	}
	auto x = N - lastPos;
	ans += x >= last ? x - last : x;

	writeln(ans);
	stdout.flush();
}