#include <bits/stdc++.h>
using namespace std;

const int MOD = 1000000007;
const int MAXN = 100005;
long long fact[MAXN];

long long pow_mod(long long a, long long b) {
    long long res = 1;
    while (b > 0) {
        if (b % 2 == 1) {
            res = res * a % MOD;
        }
        a = a * a % MOD;
        b /= 2;
    }
    return res;
}

void precompute() {
    fact[0] = 1;
    for (int i = 1; i < MAXN; i++) {
        fact[i] = fact[i-1] * i % MOD;
    }
}

int main() {
    precompute();
    int N;
    cin >> N;
    vector<int> P(N+1);
    for (int i = 1; i <= N; i++) {
        cin >> P[i];
    }
    vector<bool> visited(N+1, false);
    vector<int> c(N+1, 0);
    for (int i = 1; i <= N; i++) {
        if (!visited[i]) {
            int len = 0;
            int cur = i;
            while (!visited[cur]) {
                visited[cur] = true;
                cur = P[cur];
                len++;
            }
            c[len]++;
        }
    }
    bool S = true;
    for (int k = 1; k <= N; k++) {
        if (c[k] == 0) continue;
        if (k % 2 == 0) {
            S = false;
        }
        if (c[k] >= 2) {
            S = false;
        }
    }
    long long C = 1;
    for (int k = 1; k <= N; k++) {
        if (c[k] == 0) continue;
        long long pow_k = pow_mod(k, c[k]);
        C = C * pow_k % MOD;
        C = C * fact[c[k]] % MOD;
    }
    long long inv_C = pow_mod(C, MOD-2);
    long long total_Q = fact[N] * inv_C % MOD;
    long long ans;
    if (S && N >= 2) {
        long long inv2 = pow_mod(2, MOD-2);
        ans = total_Q * inv2 % MOD;
    } else {
        ans = total_Q % MOD;
    }
    cout << ans << endl;
    return 0;
}