lanqiao oj 1085 小猪存钱罐

#include<iostream>
#include<algorithm>
#include<cstring>
 
using namespace std ;
const int N = 1e6 +10 ;
int n ;
int s[N] ;
int find(int x ){
  if(x != s[x]) s[x] = find(s[x]);
  return s[x] ; 
}
int main(){
  cin >> n ;
  for(int i = 1 ; i <= n ;i ++) s[i] = i ;
  for(int i = 1 ; i <= n ; i++){
    int x ; cin >> x ;
    if(find(i) != find(x)) s[i] = find(x) ;
  }
  int cnt = 0 ;
  for(int i = 1 ; i <= n ; i++) if(s[i] == i) cnt ++ ;
  cout << cnt << endl ; 
}