#include #include #include #include #include #include #include #include #include #include #include #include #include #define debug_value(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << #x << "=" << x << endl; #define debug(x) cerr << "line" << __LINE__ << ":<" << __func__ << ">:" << x << endl; template inline bool chmax(T& a, T b) { if (a < b) { a = b; return 1; } return 0; } template inline bool chmin(T& a, T b) { if (a > b) { a = b; return 1; } return 0; } using namespace std; typedef long long ll; template vector> vec2d(int n, int m, T v){ return vector>(n, vector(m, v)); } template vector>> vec3d(int n, int m, int k, T v){ return vector>>(n, vector>(m, vector(k, v))); } template void print_vector(vector v, char delimiter=' '){ if(v.empty()) { cout << endl; return; } for(int i = 0; i+1 < v.size(); i++) cout << v[i] << delimiter; cout << v.back() << endl; } const ll MOD = 1000000007; class ModInt{ public: ll v; ModInt(ll _v = 0){ if(_v < 0) _v = (_v%MOD)+MOD; if(_v >= MOD) _v %= MOD; v = _v; } ModInt operator+(ll n){ return ModInt((v+n)%MOD); } ModInt operator-(ll n){ return ModInt((v-n+MOD)%MOD); } ModInt operator*(ll n){ if(n >= MOD) n %= MOD; return ModInt((v*n)%MOD); } ModInt operator/(ll n){ return ModInt((ModInt(n).inv()*v).v%MOD); } ModInt &operator+=(ll n){ v = (v+n)%MOD; return *this; } ModInt &operator-=(ll n){ v = (v-n+MOD)%MOD; return *this; } ModInt &operator*=(ll n){ v = (v*n+MOD)%MOD; return *this; } ModInt operator+(ModInt n){ return ModInt((v+n.v)%MOD); } ModInt operator-(ModInt n){ return ModInt((v-n.v+MOD)%MOD); } ModInt operator*(ModInt n){ return ModInt((v*n.v)%MOD); } ModInt operator/(ModInt n){ return ModInt((n.inv()*v).v%MOD); } ModInt &operator+=(ModInt n){ v = (v+n.v)%MOD; return *this; } ModInt &operator-=(ModInt n){ v = (v-n.v+MOD)%MOD; return *this; } ModInt &operator*=(ModInt n){ v = (v*n.v)%MOD; return *this; } bool operator==(ModInt n){ return v == n.v; } bool operator!=(ModInt n){ return v != n.v; } ModInt &operator=(ll n){ v = n%MOD; return *this; } ModInt inv(){ if(v == 1) return ModInt(1); else return ModInt(MOD-ModInt(MOD%v).inv().v*(MOD/v)%MOD); } }; ostream& operator<<(ostream& os, const ModInt& m){ os << m.v; return os; } istream & operator >> (istream &in, ModInt &m){ in >> m.v; return in; } ModInt pow(ModInt a, ll n) { assert(n >= 0); ModInt ans = 1; while (n > 0) { if (n&1) ans = ans*a; a = a*a; n >>= 1; } return ans; } struct UnionFind { vector data; UnionFind(int size) : data(size, -1) {} bool unionSet(int x, int y) { x = root(x); y = root(y); if (x != y) { if (data[y] < data[x]) swap(x, y); data[x] += data[y]; data[y] = x; } return x != y; } bool findSet(int x, int y) { return root(x) == root(y); } int root(int x) { return data[x] < 0 ? x : data[x] = root(data[x]); } int size(int x) { return -data[root(x)]; } }; #define N_MAX 200002 ModInt inv[N_MAX],fac[N_MAX],finv[N_MAX]; void init(){ fac[0]=1;fac[1]=1; finv[0]=1;finv[1]=1; inv[1]=1; for(int i=2;i a){ vector p(n); iota(p.begin(), p.end(), 0); auto ok = [&](vector p){ auto b = vector(n); iota(b.begin(), b.end(), 0); for(int i = 0; i < m; i++){ for(int j = 0; j < n; j++){ b[j] = p[b[j]]; } } for(int i = 0; i < n; i++){ if(b[i] != a[i]) return false; } return true; }; int ans = 0; do{ if(ok(p)) { // print_vector(p); ans++; } }while(next_permutation(p.begin(), p.end())); return ans; } mint solve(int n, int m, vector a){ UnionFind uf(n); for(int i = 0; i < n; i++) { uf.unionSet(i, a[i]); } vector cnt(n+1); for(int i = 0; i < n; i++){ if(uf.root(i) != i) continue; cnt[uf.size(i)]++; } mint ans = 1; for(int x = 1; x <= n; x++) { if(cnt[x] == 0) continue; vector pattern(cnt[x]+1, 0); for(int c = 1; c <= cnt[x]; c++){ int n_cycle = x*c; if(x == 1){ if(m%n_cycle == 0) pattern[c] = fac[c-1].v; continue; } if(m%n_cycle != 0){ int xx = m%n_cycle; // debug_value(xx) if(xx%c == 0){ int cc = xx/c; if(gcd(cc, x) == 1) pattern[c] = 1; } } } auto dp = vec2d(cnt[x]+1, cnt[x]+1, mint(0)); // cout << x << ':'; // print_vector(pattern); dp[0][0] = 1; for(int c = 1; c <= cnt[x]; c++){ if(c >= 2){ pattern[c] *= pow(mint(x), c-1); } for(int j = 0; j <= cnt[x]; j++){ mint select = 1; int rem = cnt[x]-j; for(int k = 0; j+k*c <= cnt[x]; k++){ if(k > 0) select *= comb(rem, c)*pattern[c]; dp[c][j+k*c] += dp[c-1][j]*select*finv[k]; if(k > 0) rem -= c; } } // print_vector(dp[c]); } // debug_value(cnt[x]) // debug_value(dp[cnt[x]][cnt[x]]) ans *= dp[cnt[x]][cnt[x]]; } return ans; } int main(){ ios::sync_with_stdio(false); cin.tie(0); cout << setprecision(10) << fixed; init(); int n, m; cin >> n >> m; vector a(n); for(int i = 0; i < n; i++) { cin >> a[i]; a[i]--; } cout << solve(n, m, a) << endl; // cout << naive(n, m, a) << endl; // iota(a.begin(), a.end(), 0); // do{ // if(solve(n, m, a).v != naive(n, m, a)) print_vector(a); // }while(next_permutation(a.begin(), a.end())); }