#include <bits/stdc++.h>
// created [2020/01/31] 22:43:02
#pragma GCC diagnostic ignored "-Wsign-compare"
#pragma GCC diagnostic ignored "-Wsign-conversion"

using i32   = int32_t;
using i64   = int64_t;
using u32   = uint32_t;
using u64   = uint64_t;
using uint  = unsigned int;
using usize = std::size_t;
using ll    = long long;
using ull   = unsigned long long;
using ld    = long double;
template<typename T, usize n>
using arr = T (&)[n];
template<typename T, usize n>
using c_arr = const T (&)[n];
template<typename T>
using max_heap = std::priority_queue<T>;
template<typename T>
using min_heap = std::priority_queue<T, std::vector<T>, std::greater<T>>;
template<typename T> constexpr T popcount(const T u) { return u ? static_cast<T>(__builtin_popcountll(static_cast<u64>(u))) : static_cast<T>(0); }
template<typename T> constexpr T log2p1(const T u) { return u ? static_cast<T>(64 - __builtin_clzll(static_cast<u64>(u))) : static_cast<T>(0); }
template<typename T> constexpr T msbp1(const T u) { return log2p1(u); }
template<typename T> constexpr T lsbp1(const T u) { return __builtin_ffsll(u); }
template<typename T> constexpr T clog(const T u) { return u ? log2p1(u - 1) : static_cast<T>(u); }
template<typename T> constexpr bool ispow2(const T u) { return u and (static_cast<u64>(u) & static_cast<u64>(u - 1)) == 0; }
template<typename T> constexpr T ceil2(const T u) { return static_cast<T>(1) << clog(u); }
template<typename T> constexpr T floor2(const T u) { return u == 0 ? static_cast<T>(0) : static_cast<T>(1) << (log2p1(u) - 1); }
template<typename T> constexpr bool btest(const T mask, const usize ind) { return static_cast<bool>((static_cast<u64>(mask) >> ind) & static_cast<u64>(1)); }
template<typename T> void bset(T& mask, const usize ind) { mask |= (static_cast<T>(1) << ind); }
template<typename T> void breset(T& mask, const usize ind) { mask &= ~(static_cast<T>(1) << ind); }
template<typename T> void bflip(T& mask, const usize ind) { mask ^= (static_cast<T>(1) << ind); }
template<typename T> void bset(T& mask, const usize ind, const bool b) { (b ? bset(mask, ind) : breset(mask, ind)); }
template<typename T> constexpr T bcut(const T mask, const usize ind) { return ind == 0 ? static_cast<T>(0) : static_cast<T>((static_cast<u64>(mask) << (64 - ind)) >> (64 - ind)); }
template<typename T> bool chmin(T& a, const T& b) { return (a > b ? a = b, true : false); }
template<typename T> bool chmax(T& a, const T& b) { return (a < b ? a = b, true : false); }
constexpr unsigned int mod                  = 1000000007;
template<typename T> constexpr T inf_v      = std::numeric_limits<T>::max() / 4;
template<typename Real> constexpr Real pi_v = Real{3.141592653589793238462643383279502884};
auto mfp = [](auto&& f) { return [=](auto&&... args) { return f(f, std::forward<decltype(args)>(args)...); }; };

template<typename T>
T in()
{
    T v;
    return std::cin >> v, v;
}
template<typename T, typename Uint, usize n, usize i>
T in_v(typename std::enable_if<(i == n), c_arr<Uint, n>>::type) { return in<T>(); }
template<typename T, typename Uint, usize n, usize i>
auto in_v(typename std::enable_if<(i < n), c_arr<Uint, n>>::type& szs)
{
    const usize s = (usize)szs[i];
    std::vector<decltype(in_v<T, Uint, n, i + 1>(szs))> ans(s);
    for (usize j = 0; j < s; j++) { ans[j] = in_v<T, Uint, n, i + 1>(szs); }
    return ans;
}
template<typename T, typename Uint, usize n>
auto in_v(c_arr<Uint, n> szs) { return in_v<T, Uint, n, 0>(szs); }
template<typename... Types>
auto in_t() { return std::tuple<std::decay_t<Types>...>{in<Types>()...}; }
struct io_init
{
    io_init()
    {
        std::cin.tie(nullptr), std::ios::sync_with_stdio(false);
        std::cout << std::fixed << std::setprecision(20);
    }
    void clear()
    {
        std::cin.tie(), std::ios::sync_with_stdio(true);
    }
} io_setting;

int out() { return 0; }
template<typename T>
int out(const T& v) { return std::cout << v, 0; }
template<typename T>
int out(const std::vector<T>& v)
{
    for (usize i = 0; i < v.size(); i++) {
        if (i > 0) { std::cout << ' '; }
        out(v[i]);
    }
    return 0;
}
template<typename T1, typename T2>
int out(const std::pair<T1, T2>& v) { return out(v.first), std::cout << ' ', out(v.second), 0; }
template<typename T, typename... Args>
int out(const T& v, const Args... args) { return out(v), std::cout << ' ', out(args...), 0; }
template<typename... Args>
int outln(const Args... args) { return out(args...), std::cout << '\n', 0; }
template<typename... Args>
int outel(const Args... args) { return out(args...), std::cout << std::endl, 0; }
#    define SHOW(...) static_cast<void>(0)
constexpr ull TEN(const usize n) { return n == 0 ? 1ULL : TEN(n - 1) * 10ULL; }

template<typename T, typename Uint, usize n, usize i>
auto make_v(typename std::enable_if<(i == n), c_arr<Uint, n>>::type, const T& v = T{}) { return v; }
template<typename T, typename Uint, usize n, usize i>
auto make_v(typename std::enable_if<(i < n), c_arr<Uint, n>>::type szs, const T& v = T{})
{
    const usize s = (usize)szs[i];
    return std::vector<decltype(make_v<T, Uint, n, i + 1>(szs, v))>(s, make_v<T, Uint, n, i + 1>(szs, v));
}
template<typename T, typename Uint, usize n>
auto make_v(c_arr<Uint, n> szs, const T& t = T{}) { return make_v<T, Uint, n, 0>(szs, t); }



template<typename T> T gcd(const T& a, const T& b) { return a < 0 ? gcd(-a, b) : b < 0 ? gcd(a, -b) : (a > b ? gcd(b, a) : a == 0 ? b : gcd(b % a, a)); }
template<typename T> T lcm(const T& a, const T& b) { return a / gcd(a, b) * b; }
template<typename T>
constexpr std::pair<T, T> extgcd(const T a, const T b)
{
    if (b == 0) { return std::pair<T, T>{1, 0}; }
    const auto g = gcd(a, b), da = std::abs(b) / g;
    const auto p = extgcd(b, a % b);
    const auto x = (da + p.second % da) % da, y = (g - a * x) / b;
    return {x, y};
}
template<typename T>
constexpr T inverse(const T a, const T mod) { return extgcd(a, mod).first; }
template<uint mod_value, bool dynamic = false>
class modint_base
{
public:
    template<typename UInt = uint>
    static std::enable_if_t<dynamic, const UInt> mod() { return mod_ref(); }
    template<typename UInt = uint>
    static constexpr std::enable_if_t<not dynamic, const UInt> mod() { return mod_value; }
    template<typename UInt = uint>
    static void set_mod(const std::enable_if_t<dynamic, const UInt> mod) { mod_ref() = mod, inv_ref() = {1, 1}; }
    modint_base() : v{0} {}
    modint_base(const ll val) : v{norm(static_cast<uint>(val % static_cast<ll>(mod()) + static_cast<ll>(mod())))} {}
    modint_base(const modint_base& n) : v{n()} {}
    explicit operator bool() const { return v != 0; }
    bool operator!() const { return not static_cast<bool>(*this); }
    modint_base& operator=(const modint_base& m) { return v = m(), (*this); }
    modint_base& operator=(const ll val) { return v = norm(uint(val % static_cast<ll>(mod()) + static_cast<ll>(mod()))), (*this); }
    friend modint_base operator+(const modint_base& m) { return m; }
    friend modint_base operator-(const modint_base& m) { return make(norm(mod() - m.v)); }
    friend modint_base operator+(const modint_base& m1, const modint_base& m2) { return make(norm(m1.v + m2.v)); }
    friend modint_base operator-(const modint_base& m1, const modint_base& m2) { return make(norm(m1.v + mod() - m2.v)); }
    friend modint_base operator*(const modint_base& m1, const modint_base& m2) { return make(static_cast<uint>(static_cast<ll>(m1.v) * static_cast<ll>(m2.v) % static_cast<ll>(mod()))); }
    friend modint_base operator/(const modint_base& m1, const modint_base& m2) { return m1 * inv(m2.v); }
    friend modint_base operator+(const modint_base& m, const ll val) { return modint_base{static_cast<ll>(m.v) + val}; }
    friend modint_base operator-(const modint_base& m, const ll val) { return modint_base{static_cast<ll>(m.v) - val}; }
    friend modint_base operator*(const modint_base& m, const ll val) { return modint_base{static_cast<ll>(m.v) * (val % static_cast<ll>(mod()))}; }
    friend modint_base operator/(const modint_base& m, const ll val) { return modint_base{static_cast<ll>(m.v) * inv(val)}; }
    friend modint_base operator+(const ll val, const modint_base& m) { return modint_base{static_cast<ll>(m.v) + val}; }
    friend modint_base operator-(const ll val, const modint_base& m) { return modint_base{-static_cast<ll>(m.v) + val}; }
    friend modint_base operator*(const ll val, const modint_base& m) { return modint_base{static_cast<ll>(m.v) * (val % static_cast<ll>(mod()))}; }
    friend modint_base operator/(const ll val, const modint_base& m) { return modint_base{val * inv(static_cast<ll>(m.v))}; }
    friend modint_base& operator+=(modint_base& m1, const modint_base& m2) { return m1 = m1 + m2; }
    friend modint_base& operator-=(modint_base& m1, const modint_base& m2) { return m1 = m1 - m2; }
    friend modint_base& operator*=(modint_base& m1, const modint_base& m2) { return m1 = m1 * m2; }
    friend modint_base& operator/=(modint_base& m1, const modint_base& m2) { return m1 = m1 / m2; }
    friend modint_base& operator+=(modint_base& m, const ll val) { return m = m + val; }
    friend modint_base& operator-=(modint_base& m, const ll val) { return m = m - val; }
    friend modint_base& operator*=(modint_base& m, const ll val) { return m = m * val; }
    friend modint_base& operator/=(modint_base& m, const ll val) { return m = m / val; }
    friend modint_base operator^(const modint_base& m, const ll n) { return power(m.v, n); }
    friend modint_base& operator^=(modint_base& m, const ll n) { return m = m ^ n; }
    friend bool operator==(const modint_base& m1, const modint_base& m2) { return m1.v == m2.v; }
    friend bool operator!=(const modint_base& m1, const modint_base& m2) { return not(m1 == m2); }
    friend bool operator==(const modint_base& m, const ll val) { return m.v == norm(static_cast<uint>(static_cast<ll>(mod()) + val % static_cast<ll>(mod()))); }
    friend bool operator!=(const modint_base& m, const ll val) { return not(m == val); }
    friend bool operator==(const ll val, const modint_base& m) { return m.v == norm(static_cast<uint>(static_cast<ll>(mod()) + val % static_cast<ll>(mod()))); }
    friend bool operator!=(const ll val, const modint_base& m) { return not(m == val); }
    friend std::istream& operator>>(std::istream& is, modint_base& m)
    {
        ll v;
        return is >> v, m = v, is;
    }
    friend std::ostream& operator<<(std::ostream& os, const modint_base& m) { return os << m(); }
    uint operator()() const { return v; }
    static modint_base small_inv(const usize n)
    {
        auto& in = inv_ref();
        if (n < in.size()) { return in[n]; }
        for (usize i = in.size(); i <= n; i++) { in.push_back(-in[modint_base::mod() % i] * (modint_base::mod() / i)); }
        return in.back();
    }
    std::pair<ll, ll> quad() const
    {
        const auto ans = quad_r(v, mod());
        ll x = std::get<0>(ans), y = std::get<1>(ans);
        if (y < 0) { x = -x, y = -y; }
        return {x, y};
    }

private:
    static std::tuple<ll, ll, ll> quad_r(const ll r, const ll p)  // r = x/y (mod p), (x,y,z) s.t. x=yr+pz
    {
        if (std::abs(r) <= 1000) { return {r, 1, 0}; }
        ll nr = p % r, q = p / r;
        if (nr * 2LL >= r) { nr -= r, q++; }
        if (nr * 2LL <= -r) { nr += r, q--; }
        const auto sub = quad_r(nr, r);
        const ll x = std::get<0>(sub), z = std::get<1>(sub), y = std::get<2>(sub);
        return {x, y - q * z, z};
    }

    template<typename UInt = uint>
    static std::enable_if_t<dynamic, UInt&> mod_ref()
    {
        static UInt mod = 0;
        return mod;
    }
    static uint norm(const uint x) { return x < mod() ? x : x - mod(); }
    static modint_base make(const uint x)
    {
        modint_base m;
        return m.v = x, m;
    }
    static modint_base power(modint_base x, ull n)
    {
        modint_base ans = 1;
        for (; n; n >>= 1, x *= x) {
            if (n & 1) { ans *= x; }
        }
        return ans;
    }
    static modint_base inv(const ll v) { return v <= 2000000 ? small_inv(static_cast<usize>(v)) : modint_base{inverse(v, static_cast<ll>(mod()))}; }
    static std::vector<modint_base>& inv_ref()
    {
        static std::vector<modint_base> in{1, 1};
        return in;
    }
    uint v;
};
template<uint mod>
using modint = modint_base<mod, false>;
template<uint id>
using dynamic_modint = modint_base<id, true>;
template<uint mod_value, bool dynamic = false>
class modcomb_base
{
public:
    using value_type = modint_base<mod_value, dynamic>;
    modcomb_base()   = delete;
    static void set_mod(const uint mod) { value_type::set_mod(mod), fact_ref() = {1, 1}, inv_fact_ref() = {1, 1}; }
    static value_type fact(const usize n)
    {
        auto& f = fact_ref();
        if (n < f.size()) { return f[n]; }
        for (usize i = f.size(); i <= n; i++) { f.push_back(f.back() * i); }
        return f.back();
    }
    static value_type inv_fact(const usize n)
    {
        auto& invf = inv_fact_ref();
        if (n < invf.size()) { return invf[n]; }
        for (usize i = invf.size(); i <= n; i++) { invf.push_back(invf.back() * value_type::small_inv(i)); }
        return invf.back();
    }
    static value_type perm(const usize n, const usize k) { return k > n ? value_type{0} : fact(n) * inv_fact(n - k); }
    static value_type comb(const usize n, const usize k) { return k > n ? value_type{0} : fact(n) * inv_fact(n - k) * inv_fact(k); }

private:
    static std::vector<value_type>& fact_ref()
    {
        static std::vector<value_type> f{1, 1};
        return f;
    }
    static std::vector<value_type>& inv_fact_ref()
    {
        static std::vector<value_type> invf{1, 1};
        return invf;
    }
};
template<uint mod>
using modcomb = modcomb_base<mod, false>;
template<uint id>
using dynamic_modcomb = modcomb_base<id, true>;


template<typename Cost = usize>
struct edge
{
    using cost_type = Cost;
    usize u, v;
    Cost c;
    edge(const usize u, const usize v) : u{u}, v{v}, c{1} {}
    edge(const usize u, const usize v, const Cost& c) : u{u}, v{v}, c{c} {}
    operator usize() const { return v; }
    usize from() const { return u; }
    usize to() const { return v; }
    Cost cost() const { return c; }
    friend std::ostream& operator<<(std::ostream& os, const edge& e) { return os << e.u << "->" << e.v << ":" << e.c; }
};
template<typename Edge>
class base_graph
{
public:
    base_graph(const usize n) : v{n}, es(n), res(n) {}
    void add_edge(const usize u, const usize v, const bool bi = false)
    {
        es[u].emplace_back(u, v), res[v].emplace_back(v, u);
        if (bi) { es[v].emplace_back(v, u), res[u].emplace_back(u, v); }
    }
    template<typename Cost>
    void add_edge(const usize u, const usize v, const Cost& c, const bool bi = false)
    {
        es[u].emplace_back(u, v, c), res[v].emplace_back(v, u, c);
        if (bi) { es[v].emplace_back(v, u, c), res[u].emplace_back(u, v, c); }
    }
    std::vector<Edge>& operator[](const usize u) { return es[u]; }
    const std::vector<Edge>& operator[](const usize u) const { return es[u]; }
    std::vector<Edge>& from(const usize u) { return es[u]; }
    const std::vector<Edge>& from(const usize u) const { return es[u]; }
    std::vector<Edge>& to(const usize v) { return res[v]; }
    const std::vector<Edge>& to(const usize v) const { return res[v]; }
    usize size() const { return v; }
    friend std::ostream& operator<<(std::ostream& os, const base_graph& g)
    {
        for (usize i = 0; i < g.v; i++) {
            for (const auto& e : g.es[i]) { os << e << '\n'; }
        }
        return os;
    }

private:
    usize v;
    std::vector<std::vector<Edge>> es, res;
};
template<typename Edge>
using base_tree = base_graph<Edge>;
using graph     = base_graph<edge<>>;
using tree      = base_graph<edge<>>;
template<typename Cost>
using cost_graph = base_graph<edge<Cost>>;
template<typename Cost>
using cost_tree = base_graph<edge<Cost>>;
template<typename Edge = edge<>>
class lowlink_manager
{
private:
    using P = std::pair<usize, usize>;
    const usize sz;
    std::vector<P> bs;
    std::vector<usize> ord, low, as;
    std::vector<bool> is_a;
    std::vector<std::vector<usize>> dfs_tree;

public:
    lowlink_manager(const base_tree<Edge>& g) : sz(g.size()), ord(sz, sz), low(sz, sz), is_a(sz, false), dfs_tree(sz)
    {
        usize num = 0;
        auto dfs  = [&](auto&& self, const usize s, const usize p) -> void {
            ord[s] = low[s] = num++;
            usize back      = 0;
            for (const auto& e : g[s]) {
                const usize to = e.to();
                if (ord[to] == sz) {
                    dfs_tree[s].push_back(to), self(self, to, s), low[s] = std::min(low[s], low[to]);
                } else {
                    if (p == to) { back++; }
                    if (p != to or back > 1) { low[s] = std::min(low[s], ord[to]); }
                }
            }
        };
        auto dfs2 = [&](auto&& self, const usize s) -> void {
            usize max = 0;
            for (const usize to : dfs_tree[s]) {
                max = std::max(max, low[to]);
                if (this->is_bridge(s, to)) { bs.push_back(std::minmax(s, to)); }
                self(self, to);
            }
            is_a[s] = ord[s] <= max and (s != 0 or dfs_tree[s].size() > 1);
            if (is_a[s]) { as.push_back(s); }
        };
        for (usize i = 0; i < sz; i++) {
            if (ord[i] != sz) { continue; }
            dfs(dfs, i, sz), dfs2(dfs2, i);
        }
    }
    bool is_art(const usize i) const { return is_a[i]; }
    bool is_bridge(const usize i, const usize j) const { return (ord[i] < ord[j]) ? ord[i] < low[j] : ord[j] < low[i]; }
    const std::vector<P>& bridges() const { return bs; }
    const std::vector<usize>& arts() const { return as; }
};

class unionfind
{
public:
    unionfind(const usize sz) : sz{sz}, rt(sz), comp_sz(sz, 1) { std::iota(rt.begin(), rt.end(), 0); }
    usize root_of(const usize a) { return assert(a < sz), rt[a] == a ? a : rt[a] = root_of(rt[a]); }
    bool unite(usize a, usize b)
    {
        assert(a < sz), assert(b < sz), a = root_of(a), b = root_of(b);
        if (a == b) { return false; }
        if (comp_sz[a] < comp_sz[b]) { std::swap(a, b); }
        return comp_sz[a] += comp_sz[b], rt[b] = a, true;
    }
    usize size_of(const usize a) { return assert(a < sz), comp_sz[root_of(a)]; }
    friend std::ostream& operator<<(std::ostream& os, const unionfind& uf)
    {
        os << "[";
        for (usize i = 0; i < uf.sz; i++) { os << uf.rt[i] << (i + 1 == uf.sz ? "" : ","); }
        return (os << "]\n");
    }

private:
    const usize sz;
    std::vector<usize> rt, comp_sz;
};
int main()
{
    using mint   = modint<mod>;
    using moc    = modcomb<mod>;
    const auto N = in<int>();
    std::vector<int> as(N);
    for (int i = 0; i < N; i++) { as[i] = in<int>() - 1; }
    graph g(N);
    unionfind uf(N);
    for (int i = 0; i < N; i++) {
        g.add_edge(i, as[i]);
        uf.unite(as[i], i);
    }
    auto comp = make_v<std::vector<int>>({N});
    for (int i = 0; i < N; i++) { comp[uf.root_of(i)].push_back(i); }
    std::vector<bool> is_loop(N, false);
    std::vector<int> dim(N, 0);
    std::vector<int> Cs;               // サイクル
    std::vector<std::vector<int>> Ds;  // サイクル+枝
    for (int id = 0; id < N; id++) {
        if (comp[id].empty()) { continue; }
        const int sz = comp[id].size();
        int r        = comp[id].front();
        for (int i = 0; i < sz; i++) { r = as[r]; }
        std::vector<int> loops;
        for (; not is_loop[r];) { loops.push_back(r), is_loop[r] = true, r = as[r]; }
        const int l = loops.size();
        std::vector<int> hs(l, 0);
        for (int i = 0; i < l; i++) {
            hs[i] = mfp([&](auto&& self, const int s) -> int {
                int d = 0, h = 0;
                for (const int from : g.to(s)) {
                    if (is_loop[from]) { continue; }
                    chmax(h, self(self, from) + 1), d++;
                }
                return dim[s] = d, h;
            })(loops[i]);
        }
        for (const int v : comp[id]) {
            if (dim[v] >= 2) { return outln(0); }
        }
        if (hs == std::vector<int>(l, 0)) {
            Cs.push_back(l);
        } else {
            Ds.push_back(hs);
        }
    }
    mint namori = 1;
    for (const auto& d : Ds) {
        const int l = d.size();
        for (int i = 0; i < l; i++) {
            if (d[i] == 0) { continue; }
            mint p = 2;
            for (int j = 1; j < d[i]; j++) {
                if (d[(i - j + l) % l] != 0) { p = 0; }
            }
            if (p == 2 and d[(i - d[i] + l) % l] != 0) { p = 1; }
            namori *= p;
        }
    }
    SHOW(namori);
    std::vector<int> num(N + 1, 0);
    for (const int c : Cs) { num[c]++; }
    mint cycle = 1;
    for (int i = 1; i <= N; i++) {
        if (num[i] == 0) { continue; }
        const int n = num[i];
        SHOW(n);
        const mint p = (i % 2 == 1 and i > 1 ? 2 : 1);
        mint sub     = 0;
        mint choose  = 1;
        for (int m = 0; 2 * m <= n; m++) {
            sub += (mint(i) ^ m) * (p ^ (n - 2 * m)) * moc::comb(n, 2 * m) * choose;
            choose *= (2 * m + 1);
        }
        SHOW(sub);
        cycle *= sub;
    }
    SHOW(cycle);
    outln(namori * cycle);
    return 0;
}


Measured memory_bytes: 21496