#include <cstdio>
#include <cstring>
#include <iostream>
#include <string>
#include <cmath>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <deque>
#include <algorithm>
#include <complex>
#include <unordered_map>
#include <unordered_set>
#include <random>
#include <cassert>
#include <fstream>
#include <utility>
#include <functional>
#include <time.h>
#include <stack>
#include <array>
#include <list>
#include <atcoder/all>
#define popcount __builtin_popcount
using namespace std;
using namespace atcoder;
typedef long long ll;
typedef pair<int, int> P;
using mint=modint1000000007;
mint f[2000010], invf[2000010];
void fac(int n){
    f[0]=1;
    for(ll i=1; i<=n; i++) f[i]=f[i-1]*i;
    invf[n]=f[n].inv();
    for(ll i=n-1; i>=0; i--) invf[i]=invf[i+1]*(i+1);
}
mint comb(int x, int y){
    if(!(0<=y && y<=x)) return 0;
    return f[x]*invf[y]*invf[x-y];
}
int main()
{
    int n; cin>>n;
    int p[100010];
    for(int i=0; i<n; i++){
        cin>>p[i];
        p[i]--;
    }
    vector<int> v;
    bool used[100010]={};
    for(int i=0; i<n; i++){
        if(used[i]) continue;
        int c=0, x=i;
        do{
            used[x]=1;
            x=p[x];
            c++;
        }while(!used[x]);
        v.push_back(c);
    }
    bool allodd=1;
    for(auto c:v) if(c%2==0) allodd=0;
    fac(n);
    map<int, int> mp;
    for(auto c:v) mp[c]++;
    if(!allodd){
        mint ans=f[n];
        for(auto c:v) ans/=c;
        for(auto p:mp) ans*=invf[p.second];
        cout<<ans.val()<<endl;
    }else{
        mint ans=f[n];
        bool all1=1;
        for(auto c:v){
            if(c>1) all1=0;
        }
        if(all1) cout<<1<<endl;
        else{
            for(auto c:v) ans/=c;
            ans/=2;
            cout<<ans.val()<<endl;
        }
    }
    return 0;
}