#include <iostream>

#include <cstdio>

#include <string>

#include <algorithm>

#include <stdlib.h>

#include <vector>

#include <cmath>

#include <queue>

#include <set>

#include <stack>

using namespace std;

#define LL long long

int p[][],o[],flag[],nt[];

LL dp[];

LL temp;

void dfs(int x)

{

    flag[x] = ;

    temp *= dp[x];

    if(flag[nt[x]] == )

    return ;

    flag[nt[x]] = ;

    dfs(nt[x]);

}

class InvariantSets

{

    public :

    LL countSets(vector <int> f)

    {

        int i,j,n,z;

        LL ans = ;

        n = f.size();

        for(i = ;i < n;i ++)

        {

            p[i][f[i]] = ;

            dp[i] = ;

            nt[i] = f[i];

            o[f[i]] ++;

        }

        for(;;)

        {

            z = ;

            for(i = ;i < n;i ++)

            {

                if(o[i] == &&!flag[i])

                {

                    flag[i] = ;

                    z = ;

                    for(j = ;j < n;j ++)

                    {

                        if(p[i][j] == &&!flag[j])

                        {

                            dp[j] *= (dp[i] + );

                            o[j] --;

                        }

                    }

                }

            }

            if(!z) break;

        }

        for(i = ;i < n;i ++)

        {

            temp = ;

            if(flag[i] == )

            {

                dfs(i);

                ans *= (temp+);

            }

        }

        return ans;

    }

};