/** * @FileName a.cpp * @Author kanpurin * @Created 2021.02.12 23:24:38 **/ #include "bits/stdc++.h" using namespace std; typedef long long ll; class UnionFind { private: vector par; public: UnionFind(int n) { par.resize(n, -1); } int root(int x) { if (par[x] < 0) return x; return par[x] = root(par[x]); } bool unite(int x, int y) { int rx = root(x); int ry = root(y); if (rx == ry) return false; if (size(rx) < size(ry)) swap(rx, ry); par[rx] += par[ry]; par[ry] = rx; return true; } bool same(int x, int y) { int rx = root(x); int ry = root(y); return rx == ry; } int size(int x) { return -par[root(x)]; } }; template< int MOD > struct mint { public: long long x; mint(long long x = 0) :x((x%MOD+MOD)%MOD) {} mint(std::string &s) { long long z = 0; for (int i = 0; i < s.size(); i++) { z *= 10; z += s[i] - '0'; z %= MOD; } this->x = z; } mint& operator+=(const mint &a) { if ((x += a.x) >= MOD) x -= MOD; return *this; } mint& operator-=(const mint &a) { if ((x += MOD - a.x) >= MOD) x -= MOD; return *this; } mint& operator*=(const mint &a) { (x *= a.x) %= MOD; return *this; } mint& operator/=(const mint &a) { long long n = MOD - 2; mint u = 1, b = a; while (n > 0) { if (n & 1) { u *= b; } b *= b; n >>= 1; } return *this *= u; } mint operator+(const mint &a) const { mint res(*this); return res += a; } mint operator-() const {return mint() -= *this; } mint operator-(const mint &a) const { mint res(*this); return res -= a; } mint operator*(const mint &a) const { mint res(*this); return res *= a; } mint operator/(const mint &a) const { mint res(*this); return res /= a; } friend std::ostream& operator<<(std::ostream &os, const mint &n) { return os << n.x; } friend std::istream &operator>>(std::istream &is, mint &n) { long long x; is >> x; n = mint(x); return is; } bool operator==(const mint &a) const { return this->x == a.x; } bool operator!=(const mint &a) const { return this->x != a.x; } mint pow(long long k) const { mint ret = 1; mint p = this->x; while (k > 0) { if (k & 1) { ret *= p; } p *= p; k >>= 1; } return ret; } }; constexpr int MOD = 998244353; template struct Combination { private: int N; public: vector< T > FACT, IFACT; Combination(int n) : N(n) { FACT.resize(n + 1); IFACT.resize(n + 1); FACT[0] = 1; for (int i = 1; i <= n; i++) { FACT[i] = FACT[i - 1] * i; } IFACT[n] = T(1) / FACT[n]; for (int i = n-1; i >= 0; i--) { IFACT[i] = IFACT[i+1] * (i+1); } } T comb(int n, int r) { if (n < 0 || r < 0 || r > n) return 0; if (r > n / 2) r = n - r; return FACT[n] * IFACT[n - r] * IFACT[r]; } }; int main() { int n,m;cin >> n >> m; UnionFind uf(n); Combination> cb(m); for (int i = 0; i < n; i++) { int p;cin >> p; uf.unite(p-1,i); } vector>> f(n+1,vector>(m+1)); for (int i = 0; i < n-1; i++) { if (i == 0) { for (int j = 0; j < m-1; j++) { f[i+2][j+2] = mint(j+2)*(j+1); } } else { for (int j = 0; j < m-1; j++) { f[i+2][j+2] = f[i+1][j+2]*j+f[i][j+2]*(j+1); } } } vector c; for (int i = 0; i < n; i++) { if (uf.root(i) == i) { c.push_back(uf.size(i)); } } mint ans = 0; for (int i = 0; i <= m; i++) { mint total = 1; for (int j = 0; j < c.size(); j++) { total *= f[c[j]][i]; } if ((i & 1) == (m & 1)) { ans += total * cb.comb(m,i); } else { ans -= total * cb.comb(m,i); } } cout << ans * cb.IFACT[m] << endl; return 0; }