package main

import . "fmt"

func main() {
	var n int
	Scan(&n)
	ps:=make([]int,n)
	t:=map[int]bool{}
	for i:=range ps {
		Scan(&ps[i])
		t[ps[i]]=true
	}
	m:=map[int]bool{}
	for i,p:=range ps {
		if t[i+1] {
			continue
		}
		m[p]=true
	}
	a:=map[int]bool{}
	for i,p:=range ps {
		if m[i+1]&&p>0 {
			a[p]=true
		}
	}
	Println(len(a))
}