#include namespace { #pragma GCC diagnostic push #pragma GCC diagnostic ignored "-Wunused-function" #include #pragma GCC diagnostic pop using namespace std; using namespace atcoder; #define rep(i,n) for(int i = 0; i < (int)(n); i++) #define rrep(i,n) for(int i = (int)(n) - 1; i >= 0; i--) #define all(x) begin(x), end(x) #define rall(x) rbegin(x), rend(x) template bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; } template bool chmin(T& a, const T& b) { if (b < a) { a = b; return true; } else return false; } using ll = long long; using P = pair; using VI = vector; using VVI = vector; using VL = vector; using VVL = vector; using mint = modint1000000007; VI cycle_decomposition(const vector& a) { const int n = a.size(); vector visited(n); VI res; for(int i = 0; i < n; i++) if (!visited[i]) { int cnt = 0; int v = i; do { visited[v] = true; cnt++; v = a[v]; } while (v != i); res.emplace_back(cnt); } return res; } constexpr int FACT_SIZE = 1000000; mint Fact[FACT_SIZE + 1]; mint iFact[FACT_SIZE + 1]; const auto fact_init = [] { Fact[0] = mint::raw(1); for(int i = 1; i <= FACT_SIZE; ++i) { Fact[i] = Fact[i-1] * i; } iFact[FACT_SIZE] = Fact[FACT_SIZE].inv(); for(int i = FACT_SIZE; i; --i) { iFact[i-1] = iFact[i] * i; } return false; }(); mint comb(int n, int k) { if (k == 0) return mint::raw(1); assert(n >= 0 && k >= 0); if (k > n) return mint::raw(0); return Fact[n] * iFact[n - k] * iFact[k]; } mint icomb(int n, int k) { return iFact[n] * Fact[n - k] * Fact[k]; } mint fact(int n) {return Fact[n];} mint perm(int n, int k) { assert(0 <= n); return Fact[n] * iFact[n - k]; } } int main() { ios::sync_with_stdio(false); cin.tie(0); int n, m; cin >> n >> m; VI a(n); rep(i, n) cin >> a[i], a[i]--; auto cs = cycle_decomposition(a); sort(all(cs)); mint ans = 1; int sz = cs.size(); for(int i = 0; i < sz;) { int j = i + 1; while(j < sz && cs[i] == cs[j]) j++; int cnt = j - i; int len = cs[i]; vector> d; for(int i = 1; i <= cnt; i++) if (m % (i * len) == i % (i * len)) { d.emplace_back(i, mint(len).pow(i - 1)); } vector dp(cnt + 1); dp[0] = Fact[cnt]; rep(i, cnt) { dp[i] /= cnt - i; for(auto [j, v]: d) { if (i + j > cnt) break; dp[i + j] += dp[i] * v; } } ans *= dp[cnt]; i = j; } cout << ans.val() << '\n'; }