// <szp.cpp> - Thu Oct  6 08:17:54 2016
// This file is made by YJinpeng，created by XuYike's black technology automatically.
// Copyright (C) 2016 ChangJun High School, Inc.
// I don't know what this program is.

#include <iostream>
#include <vector>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <cstdlib>
#include <cmath>
#define MOD 1000000007
#define INF 1e9
#define IN inline
#define RG register
using namespace std;
typedef long long LL;
const int MAXN=1000010;
inline int max(int &x,int &y) {return x>y?x:y;}
inline int min(int &x,int &y) {return x<y?x:y;}
inline int gi() {register int w=0,q=0;register char ch=getchar();while((ch<'0'||ch>'9')&&ch!='-')ch=getchar();if(ch=='-')q=1,ch=getchar();while(ch>='0'&&ch<='9')w=w*10+ch-'0',ch=getchar();return q?-w:w;
}
int t;bool u[MAXN],k[MAXN];int f[MAXN][2],g[MAXN][2];
int fr[MAXN],to[MAXN],fa[MAXN],ne[MAXN],q[MAXN];
IN void add(int u,int v){to[++t]=v;ne[t]=fr[u];fr[u]=t;
}
IN void dfs(int i){k[i]=1;for(int j=fr[i],y;y=to[j],j;j=ne[j])dfs(y),f[i][0]+=max(f[y][0],f[y][1]);for(int j=fr[i],y;y=to[j],j;j=ne[j])f[i][1]=max(1+f[i][0]+f[y][0]-max(f[y][0],f[y][1]),f[i][1]);
}
int work(int l,int r,bool ty){g[q[r-1]][0]=g[q[r-1]][1]=0;if(ty){g[q[l]][0]=f[q[r]][1]+f[q[l]][0];g[q[l]][1]=f[q[r]][1]+f[q[l]][1];}else{g[q[l]][0]=f[q[r]][0]+f[q[l]][0];g[q[l]][1]=f[q[r]][0]+max(f[q[l]][0]+1,f[q[l]][1]?f[q[l]][1]:1);}for(int i=l+1;i<r;i++){g[q[i]][0]=max(g[q[i-1]][0],g[q[i-1]][1])+f[q[i]][0];g[q[i]][1]=max(max(g[q[i-1]][0],g[q[i-1]][1])+f[q[i]][1],max(f[q[i]][0]+1,f[q[i]][1])+g[q[i-1]][0]);}if(ty&&!f[q[r]][1])return g[q[r-1]][0]+1;//this case=0return max(g[q[r-1]][0],g[q[r-1]][1]);
}
int main()
{freopen("szp.in","r",stdin);freopen("szp.out","w",stdout);int n=gi(),ans=0;for(int i=1;i<=n;i++){fa[i]=gi();add(fa[i],i);}while(1){int x,tot=0,o;for(x=1;x<=n;x++)if(!k[x])break;if(x==n+1)break;u[q[tot=1]=x]=1;while(!u[fa[x]])x=fa[x],u[q[++tot]=x]=1;x=fa[x];for(o=tot;o;o--)if(q[o]==x)break;for(int i=1;i<=tot;i++)u[q[i]]=0;q[o-1]=q[tot];for(int i=o;i<=tot;i++){k[q[i]]=1;for(int j=fr[q[i]],y;y=to[j],j;j=ne[j])if(y!=q[i-1])dfs(y),f[q[i]][0]+=max(f[y][0],f[y][1]);for(int j=fr[q[i]],y;y=to[j],j;j=ne[j])if(y!=q[i-1])f[q[i]][1]=max(1+f[q[i]][0]+f[y][0]-max(f[y][0],f[y][1]),f[q[i]][1]);}ans+=max(work(o,tot,1),work(o,tot,0));}printf("%d",ans);return 0;
}

// <szp.cpp> - Thu Oct  6 08:07:12 2016
// This file is created by XuYike's black technology automatically.
// Copyright (C) 2015 ChangJun High School, Inc.
// I don't know what this program is.

#include <iostream>
#include <vector>
#include <queue>
#include <algorithm>
#include <cstring>
#include <cstdio>
#include <cmath>
using namespace std;
typedef long long lol;
int gi(){int res=0,fh=1;char ch=getchar();while((ch>'9'||ch<'0')&&ch!='-')ch=getchar();if(ch=='-')fh=-1,ch=getchar();while(ch>='0'&&ch<='9')res=res*10+ch-'0',ch=getchar();return fh*res;
}
const int MAXN=1000010;
const int INF=1e9;
int a[MAXN],d[MAXN];
bool vis[MAXN];
queue <int> q;
int main(){freopen("szp.in","r",stdin);freopen("szp.out","w",stdout);int n=gi();for(int i=1;i<=n;i++){a[i]=gi();d[a[i]]++;}for(int i=1;i<=n;i++)if(!d[i])q.push(i);int ans=0;while(!q.empty()){int x=q.front();q.pop();vis[x]=1;if(vis[a[x]])continue;vis[a[x]]=1;ans++;if(!--d[a[a[x]]])q.push(a[a[x]]);}for(int i=1;i<=n;i++){if(vis[i])continue;vis[i]=1;int sz=1;for(int j=a[i];j!=i;j=a[j]){vis[j]=1;sz++;}ans+=sz>>1;}printf("%d",ans);return 0;
}