from sys import stdin,setrecursionlimit#,set_int_max_str_digits
#import pypyjit
#pypyjit.set_param('max_unroll_recursion=-1')
setrecursionlimit(2000000) # これこどふぉだと無理
#set_int_max_str_digits(200010)
mod = 998244353 
ii = lambda :int(stdin.readline())
mi = lambda :map(int,stdin.readline().split())
li = lambda :list(mi())
gmi = lambda :map(lambda x: int(x) - 1, stdin.readline().split())
gi = lambda :list(map(lambda x: 0 if x == "." else 1,input())) # グリッド入力受け取り
py = lambda :print("Yes")
pn = lambda :print("No")
pf = lambda :print("First") 
ps = lambda :print("Second")
pyn = lambda x: print("Yes") if x else print("No")
vec = [(1,0),(-1,0),(0,-1),(0,1)]
vec1 = [(1,0),(1,1),(0,1),(-1,1),(-1,0),(-1,-1),(0,-1),(1,-1)] #8方向
vec2 = [(1,1),(1,0),(0,-1),(-1,-1),(-1,0),(0,1)] # 六角形グリッド
inf = 2*10**18
from collections import defaultdict,deque
from heapq import heappop,heappush


n = ii() 
a = list(gmi())

g = defaultdict(list) 

memo = [0]*n 

for i,x in enumerate(a):
    g[i].append(x) 
    if x >= 0:
        memo[x] += 1 

lev0 = []
for i in range(n):
    if memo[i] == 0:
        lev0.append(i) 

lev1 = set() 

for i in lev0:
    for v in g[i]:
        lev1.add(v) 

lev2 = set()

for i in lev1:
    for v in g[i]:
        if v >= 0:
            lev2.add(v) 

print(len(lev2))