#coding: utf-8
##yuki_182

import sys

n=int(raw_input())
s=[]
s=raw_input().split()
if len(s)!=n:
 print "error"
 sys.exit()

cnt=0
for i in xrange(len(s)):
 if int(s[i])<=0:
  print "error"
  sys.exit()
 if s.count(s[i])==1:
  cnt+=1

print cnt