#define _USE_MATH_DEFINES #include using namespace std; #define FOR(i,m,n) for(int i=(m);i<(n);++i) #define REP(i,n) FOR(i,0,n) #define ALL(v) (v).begin(),(v).end() using ll = long long; constexpr int INF = 0x3f3f3f3f; constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL; constexpr double EPS = 1e-8; constexpr int MOD = 998244353; constexpr int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1}; constexpr int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1}; template inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; } template inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; } struct IOSetup { IOSetup() { std::cin.tie(nullptr); std::ios_base::sync_with_stdio(false); std::cout << fixed << setprecision(20); } } iosetup; template struct MInt { unsigned val; MInt(): val(0) {} MInt(long long x) : val(x >= 0 ? x % MOD : x % MOD + MOD) {} static int get_mod() { return MOD; } static void set_mod(int divisor) { assert(divisor == MOD); } MInt pow(long long exponent) const { MInt tmp = *this, res = 1; while (exponent > 0) { if (exponent & 1) res *= tmp; tmp *= tmp; exponent >>= 1; } return res; } MInt &operator+=(const MInt &x) { if((val += x.val) >= MOD) val -= MOD; return *this; } MInt &operator-=(const MInt &x) { if((val += MOD - x.val) >= MOD) val -= MOD; return *this; } MInt &operator*=(const MInt &x) { val = static_cast(val) * x.val % MOD; return *this; } MInt &operator/=(const MInt &x) { // assert(std::__gcd(static_cast(x.val), MOD) == 1); unsigned a = x.val, b = MOD; int u = 1, v = 0; while (b) { unsigned tmp = a / b; std::swap(a -= tmp * b, b); std::swap(u -= tmp * v, v); } return *this *= u; } bool operator==(const MInt &x) const { return val == x.val; } bool operator!=(const MInt &x) const { return val != x.val; } bool operator<(const MInt &x) const { return val < x.val; } bool operator<=(const MInt &x) const { return val <= x.val; } bool operator>(const MInt &x) const { return val > x.val; } bool operator>=(const MInt &x) const { return val >= x.val; } MInt &operator++() { if (++val == MOD) val = 0; return *this; } MInt operator++(int) { MInt res = *this; ++*this; return res; } MInt &operator--() { val = (val == 0 ? MOD : val) - 1; return *this; } MInt operator--(int) { MInt res = *this; --*this; return res; } MInt operator+() const { return *this; } MInt operator-() const { return MInt(val ? MOD - val : 0); } MInt operator+(const MInt &x) const { return MInt(*this) += x; } MInt operator-(const MInt &x) const { return MInt(*this) -= x; } MInt operator*(const MInt &x) const { return MInt(*this) *= x; } MInt operator/(const MInt &x) const { return MInt(*this) /= x; } friend std::ostream &operator<<(std::ostream &os, const MInt &x) { return os << x.val; } friend std::istream &operator>>(std::istream &is, MInt &x) { long long val; is >> val; x = MInt(val); return is; } }; namespace std { template MInt abs(const MInt &x) { return x; } } template struct Combinatorics { using ModInt = MInt; int val; // "val!" and "mod" must be disjoint. std::vector fact, fact_inv, inv; Combinatorics(int val = 10000000) : val(val), fact(val + 1), fact_inv(val + 1), inv(val + 1) { fact[0] = 1; for (int i = 1; i <= val; ++i) fact[i] = fact[i - 1] * i; fact_inv[val] = ModInt(1) / fact[val]; for (int i = val; i > 0; --i) fact_inv[i - 1] = fact_inv[i] * i; for (int i = 1; i <= val; ++i) inv[i] = fact[i - 1] * fact_inv[i]; } ModInt nCk(int n, int k) const { if (n < 0 || n < k || k < 0) return 0; assert(n <= val && k <= val); return fact[n] * fact_inv[k] * fact_inv[n - k]; } ModInt nPk(int n, int k) const { if (n < 0 || n < k || k < 0) return 0; assert(n <= val); return fact[n] * fact_inv[n - k]; } ModInt nHk(int n, int k) const { if (n < 0 || k < 0) return 0; return k == 0 ? 1 : nCk(n + k - 1, k); } }; using ModInt = MInt; struct UnionFind { UnionFind(int n) : data(n, -1) {} int root(int ver) { return data[ver] < 0 ? ver : data[ver] = root(data[ver]); } bool unite(int u, int v) { u = root(u); v = root(v); if (u == v) return false; if (data[u] > data[v]) std::swap(u, v); data[u] += data[v]; data[v] = u; return true; } bool same(int u, int v) { return root(u) == root(v); } int size(int ver) { return -data[root(ver)]; } private: std::vector data; }; int main() { int n, m; cin >> n >> m; UnionFind uf(n); REP(i, n) { int p; cin >> p; --p; uf.unite(i, p); } vector cycle; REP(i, n) { if (uf.root(i) == i) cycle.emplace_back(uf.size(i)); } vector dp(m + 1, 0); dp[0] = 1; for (int len : cycle) { vector tmp(2, vector(m + 1, ModInt(0))); REP(j, m + 1) { tmp[true][j] += dp[j] * j; if (j + 1 <= m) tmp[true][j + 1] += dp[j] * (m - j); } FOR(i, 1, len) { vector nx(2, vector(m + 1, ModInt(0))); FOR(j, 1, m + 1) { nx[false][j] += tmp[true][j] * (j - 1); if (j + 1 <= m) nx[false][j + 1] += tmp[true][j] * (m - j); nx[true][j] += tmp[false][j]; nx[false][j] += tmp[false][j] * max(j - 2, 0); if (j + 1 <= m) nx[false][j + 1] += tmp[false][j] * (m - j); } tmp.swap(nx); } REP(j, m + 1) dp[j] = tmp[false][j]; } cout << dp[m] * Combinatorics().fact_inv[m] << '\n'; return 0; }