#include <cstdio>
#include <algorithm>
#include <stack>
#include <queue>
#include <deque>
#include <vector>
#include <string>
#include <string.h>
#include <cstdlib>
#include <ctime>
#include <cmath>
#include <map>
#include <set>
#include <iostream>
#include <sstream>
#include <numeric>
#include <cctype>
#include <bitset>
#include <cassert>
#include <random>
#define fi first
#define se second
#define rep(i,n) for(int i = 0; i < (n); ++i)
#define rrep(i,n) for(int i = 1; i <= (n); ++i)
#define drep(i,n) for(int i = (n)-1; i >= 0; --i)
#define gep(i,g,j) for(int i = g.head[j]; i != -1; i = g.e[i].next)
#define each(it,c) for(__typeof((c).begin()) it=(c).begin();it!=(c).end();it++)
#define rng(a) a.begin(),a.end()
#define maxs(x,y) x = max(x,y)
#define mins(x,y) x = min(x,y)
#define pb push_back
#define sz(x) (int)(x).size()
#define pcnt __builtin_popcount
#define uni(x) x.erase(unique(rng(x)),x.end())
#define snuke srand((unsigned)clock()+(unsigned)time(NULL));
#define df(x) int x = in()
#define dame { puts("-1"); return 0;}
#define show(x) cout<<#x<<" = "<<x<<endl;
#define PQ(T) priority_queue<T,vector<T>,greater<T> >
#define bn(x) ((1<<x)-1)
using namespace std;
typedef long long int ll;
typedef pair<int,int> P;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<ll> vl;
typedef vector<P> vp;
inline int in() { int x; scanf("%d",&x); return x;}
inline void priv(vi a) { rep(i,sz(a)) printf("%d%c",a[i],i==sz(a)-1?'\n':' ');}
template<typename T>istream& operator>>(istream&i,vector<T>&v)
{rep(j,sz(v))i>>v[j];return i;}
template<typename T>string join(vector<T>&v)
{stringstream s;rep(i,sz(v))s<<' '<<v[i];return s.str().substr(1);}
template<typename T>ostream& operator<<(ostream&o,vector<T>&v)
{if(sz(v))o<<join(v);return o;}
template<typename T1,typename T2>istream& operator>>(istream&i,pair<T1,T2>&v)
{return i>>v.fi>>v.se;}
template<typename T1,typename T2>ostream& operator<<(ostream&o,pair<T1,T2>&v)
{return o<<v.fi<<","<<v.se;}
const int MX = 100005, INF = 1001001001;
const ll LINF = 1e18;
const double eps = 1e-10;

// coordinate compression
struct X {
  typedef int T;
  vector<T> d;
  inline void add(T x) { d.pb(x);}
  void init() {
    sort(rng(d));
    d.erase(unique(rng(d)), d.end());
  }
  inline int size() { return sz(d);}
  inline int operator[](T x) { return upper_bound(rng(d),x)-d.begin()-1;}
};
//

// Union find
struct uf {
  vi d;
  uf(){}
  uf(int mx):d(mx,-1){}
  int root(int x) {
    if(d[x] < 0) return x;
    return d[x] = root(d[x]);
  }
  bool unite(int x, int y) {
    x = root(x); y = root(y);
    if(x == y) return false;
    if(d[x] > d[y]) swap(x,y);
    d[x] += d[y]; d[y] = x;
    return true;
  }
  int size(int x) { return -d[root(x)];}
};
//

// Mod int
const int mod = 1000000007;
struct mint;
mint ex(mint a, ll t);
struct mint {
  ll x;
  mint():x(0){}
  mint(ll x):x((x%mod+mod)%mod){}
  // mint(ll x):x(x){}
  mint& fix() { x = (x%mod+mod)%mod; return *this;}
  mint& operator+=(const mint& a){ if((x+=a.x)>=mod) x-=mod; return *this;}
  mint& operator-=(const mint& a){ if((x+=mod-a.x)>=mod) x-=mod; return *this;}
  mint& operator*=(const mint& a){ (x*=a.x)%=mod; return *this;}
  mint& operator/=(const mint& a){ (x*=ex(a,mod-2).x)%=mod; return *this;}
  mint operator+(const mint& a)const{ return mint(*this) += a;}
  mint operator-(const mint& a)const{ return mint(*this) -= a;}
  mint operator*(const mint& a)const{ return mint(*this) *= a;}
  mint operator/(const mint& a)const{ return mint(*this) /= a;}
  bool operator<(const mint& a)const{ return x < a.x;}
  bool operator==(const mint& a)const{ return x == a.x;}
};
istream& operator>>(istream&i,mint&a){i>>a.x;return i;}
ostream& operator<<(ostream&o,const mint&a){o<<a.x;return o;}
typedef vector<mint> vm;
mint ex(mint a, ll t) {
  if(!t) return 1;
  mint res = ex(a,t/2);
  res *= res;
  return (t&1)?res*a:res;
}
struct comb {
  vm f, g;
  comb(){}
  comb(int mx):f(mx+1),g(mx+1) {
    f[0] = 1;
    rrep(i,mx) f[i] = f[i-1]*i;
    g[mx] = ex(f[mx],mod-2);
    for(int i=mx;i>0;i--) g[i-1] = g[i]*i;
  }
  mint c(int a, int b) {
    if (a < b) return 0;
    return f[a]*g[b]*g[a-b];
  }
};
//

bool cyc;
int r; P sp;
vvi to;
map<P,mint> dp;
vi ud;
mint dfs(int a, int b, bool fst=false) {
  P p(a,b);
  if (!fst && p == sp) return 1;
  if (dp.count(p)) return dp[p];
  if (ud[b]) return 0;
  ud[b] = 1;
  mint now = 0;
  int ai = -1;
  rep(i,sz(to[a])) {
    int v = to[a][i];
    if (v == b) ai = i;
  }
  if (sz(to[a]) == 2) {
    if (~ai) now = dfs(b,to[a][ai^1]); 
  } else if (sz(to[a]) == 1 && !~ai) {
    now = dfs(b,to[a][0]); 
  } else {
    rep(i,sz(to[b])) now += dfs(b,to[b][i]);
  }
  ud[b] = 0;
  return dp[p] = now;
}
mint solve(int a, int b) {
  dp = map<P,mint>();
  ud = vi(sz(to));
  sp = P(a,b);
  return dfs(a,b,true);
}
mint f(vi a) {
  int n = sz(a);
  // cout<<a<<endl;
  to = vvi(n);
  rep(i,n) to[a[i]].pb(i);
  cyc = true;
  rep(i,n) if (sz(to[i]) != 1) cyc = false;
  rep(i,n) if (sz(to[i]) > 2) return 0;
  if (cyc) return 1;
  if (n == 2) return 1;
  r = 0;
  rep(i,n) if (sz(to[i]) == 2) r = i;
  return solve(to[r][0],to[r][1]) + solve(to[r][1],to[r][0]);
}

int main() {
  int n;
  scanf("%d",&n);
  vi a(n);
  cin >> a;
  rep(i,n) a[i]--;
  uf t(n);
  rep(i,n) t.unite(i,a[i]);
  vvi vs(n);
  rep(i,n) vs[t.root(i)].pb(i);
  vi cs(n+1);
  mint ans = 1;
  rep(i,n) {
    int m = sz(vs[i]);
    if (!m) continue;
    X xs;
    for (int v : vs[i]) xs.add(v);
    vi x(m);
    rep(j,m) x[j] = xs[a[xs.d[j]]];
    ans *= f(x);
    if (cyc) cs[m]++;
  }
  comb c(MX*2);
  rrep(ci,n) {
    if (!cs[ci]) continue;
    int m = cs[ci];
    mint sum = 0;
    rep(i,m/2+1) {
      mint now = 1;
      if ((ci&1) && ci != 1) now *= ex(2,m-i*2);
      now *= c.f[m]*c.g[m-i*2]*ex(c.g[2],i)*c.g[i]*ex(ci,i);
      sum += now;
    }
    ans *= sum;
  }
  cout<<ans<<endl;
  return 0;
}































Measured memory_bytes: 33128