/**************************************************************

     Problem: 1529

     User: Tunix

     Language: C++

     Result: Memory_Limit_Exceed

 ****************************************************************/

 //BZOJ 1529

 #include<cstdio>

 #include<cstring>

 #include<cstdlib>

 #include<iostream>

 #include<algorithm>

 #define rep(i,n) for(int i=0;i<n;++i)

 #define F(i,j,n) for(int i=j;i<=n;++i)

 #define D(i,j,n) for(int i=j;i>=n;--i)

 using namespace std;

 const int N=;

 void read(int &v){

     v=;int sign=; char ch=getchar();

     while(ch<'' || ch>'') {if (ch=='-') sign=-; ch=getchar();}

     while(ch>=''&&ch<=''){v=v*+ch-''; ch=getchar();}

     v*=sign;

 }

 /********************tamplate*******************/

 int dfn[N],low[N],dfs_clock,SCC=,belong[N],n;

 int head[N],to[N],next[N],cnt;

 void ins(int x,int y){

     to[++cnt]=y; next[cnt]=head[x]; head[x]=cnt;

 }

 int t[N],ne[N],h[N];

 void add(int x,int y){

     t[++cnt]=y; ne[cnt]=h[x]; h[x]=cnt;

 }

 bool inst[N];

 int st[N],top=;

 void tarjan(int x){

     int y;

     dfn[x]=low[x]=++dfs_clock;

     st[top++]=x;

     inst[x]=;

     for(int i=head[x];i;i=next[i]){

         y=to[i];

         if (!dfn[y]){

             tarjan(y);

             low[x]=min(low[x],low[y]);

         }

         else if (inst[y]) low[x]=min(low[x],dfn[y]);

     }

     if (dfn[x]==low[x]){

         ++SCC;

         for(y=;y!=x;){

             y=st[--top];

             inst[y]=;

             belong[y]=SCC;

         }

     }

 }

 int in[N];

 void rebuild(){

     F(x,,n)

         for(int i=head[x];i;i=next[i])

             if (belong[x]!=belong[to[i]]){

                 add(belong[x],belong[to[i]]);

                 in[belong[to[i]]]++;

             }

 }

 /***********************************************/

 int main(){

 #ifndef ONLINE_JUDGE

     freopen("1529.in","r",stdin);

 #endif

     read(n);

     int x;

     F(i,,n){

         read(x);

         ins(x,i);

     }

     F(i,,n) if (!dfn[i]) tarjan(i);

     rebuild();

     int ans=;

     F(i,,SCC) if(in[i]==) ans++;

     printf("%d\n",ans);

     return ;

 }

 /**************************************************************

     Problem: 1529

     User: Tunix

     Language: C++

     Result: Accepted

     Time:908 ms

     Memory:4712 kb

 ****************************************************************/

 //BZOJ 1529

 #include<cstdio>

 #define rep(i,n) for(int i=0;i<n;++i)

 #define F(i,j,n) for(int i=j;i<=n;++i)

 #define D(i,j,n) for(int i=j;i>=n;--i)

 using namespace std;

 const int N=;

 void read(int &v){

     v=;int sign=; char ch=getchar();

     while(ch<'' || ch>'') {if (ch=='-') sign=-; ch=getchar();}

     while(ch>=''&&ch<=''){v=v*+ch-''; ch=getchar();}

     v*=sign;

 }

 int fa[N],n;

 int getfather(int x){

     if (fa[x]!=x) fa[x]=getfather(fa[x]);

     return fa[x];

 }

 int main(){

     read(n);

     int x;

     F(i,,n) fa[i]=i;

     F(i,,n){

         read(x);

         int f1=getfather(i),f2=getfather(x);

         if (f1!=f2) fa[f1]=f2;

     }

     int ans=;

     F(i,,n) if (fa[i]==i) ans++;

     printf("%d\n",ans);

     return ;

 }