369D

#include<bits/stdc++.h>
#define up(j,k,i) for(i=j;i<k;i++)
#define down(j,k,i) for(i=j;i>k;i--)
#define M 1000000007
typedef long long int ll;
using namespace std;
ll i,j,k,z,t,n,m,sum,ans,x,y,maxm=0,minm=inf;
map<ll,ll> child;
vector par[200005];
bool vis[200005],revis[200005],permvis[200005];
stack s;
ll pow2[400005];

void dfs(ll x)
{
    if(vis[x]) return;
    vis[x]=1;

dfs(child[x]);
s.push(x);
}

void rev_dfs(ll x,ll cnt)
{
permvis[x]=1;
revis[x]=1;

    for(auto c:par[x])
    {
        if(revis[c]!=1)
        rev_dfs(c,cnt+1);

        else
        if(revis[c])
        z=1,ans=cnt+1;
    }

revis[x]=0;
}
int main()
{
fact[0]=1;
sum=1;

cin>>n;

    up(1,n+1,i)
    fact[i]=fact[i-1]*2%M;

    up(1,n+1,i)
    { cin>>x; child[i]=x; par[x].pb(i); }

    up(1,n+1,i)
    {
    if(!vis[i])
    dfs(i);
    }

while(!s.empty())
{
 ans=0; z=0;

x=s.top();
s.pop();

if(permvis[x])
continue;

rev_dfs(x,0);

if(z)
sum=sum*(fact[ans]-2)%M,y+=ans;

}

sum=sum*(fact[n-y])%M;

cout<<(sum+M)%M;

}