/** * author: otera * created: 12.02.2021 22:28:34 **/ #include using namespace std; using ll = long long; using ld = long double; using ull = unsigned long long; using uint = unsigned; const int inf=1e9+7; const ll INF=1LL<<60; #define rep(i, n) for(int i = 0; i < n; ++ i) #define per(i,n) for(int i=n-1;i>=0;i--) #define Rep(i,sta,n) for(int i=sta;i=1;i--) #define Rep1(i,sta,n) for(int i=sta;i<=n;i++) typedef pair P; typedef pair LP; #define pb push_back #define eb emplace_back #define fr first #define sc second #define all(c) c.begin(),c.end() #define lb(c, x) distance((c).begin(), lower_bound(all(c), (x))) #define ub(c, x) distance((c).begin(), upper_bound(all(c), (x))) #define Sort(a) sort(all(a)) #define Rev(a) reverse(all(a)) #define Uniq(a) sort(all(a));a.erase(unique(all(a)),end(a)) #define si(c) (int)(c).size() inline ll popcnt(ull a){ return __builtin_popcountll(a); } #define tpow(n) (1LL<<(n)) #define unless(A) if(!(A)) ll intpow(ll a, ll b){ ll ans = 1; while(b){ if(b & 1) ans *= a; a *= a; b /= 2; } return ans; } 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; } #define INT(...) int __VA_ARGS__;in(__VA_ARGS__) #define LL(...) ll __VA_ARGS__;in(__VA_ARGS__) #define ULL(...) ull __VA_ARGS__;in(__VA_ARGS__) #define STR(...) string __VA_ARGS__;in(__VA_ARGS__) #define CHR(...) char __VA_ARGS__;in(__VA_ARGS__) #define DBL(...) double __VA_ARGS__;in(__VA_ARGS__) #define LD(...) ld __VA_ARGS__;in(__VA_ARGS__) #define vec(type,name,...) vectorname(__VA_ARGS__) #define VEC(type,name,size) vectorname(size);in(name) #define vv(type,name,h,...) vector>name(h,vector(__VA_ARGS__)) #define VV(type,name,h,w) vector>name(h,vector(w));in(name) #define vvv(type,name,h,w,...) vector>>name(h,vector>(w,vector(__VA_ARGS__))) template using vc = vector; template using vvc = vector>; template using vvvc = vector>; template using vvvvc = vector>; template using pq = priority_queue; template using pqg = priority_queue, greater>; template void scan(T& a){ cin >> a; } template void scan(vector& a){ for(auto&& i : a) scan(i); } void in(){} template void in(Head& head, Tail&... tail){ scan(head); in(tail...); } void print(){ cout << ' '; } template void print(const T& a){ cout << a; } template void print(const vector& a){ if(a.empty()) return; print(a[0]); for(auto i = a.begin(); ++i != a.end(); ){ cout << ' '; print(*i); } } int out(){ cout << '\n'; return 0; } template int out(const T& t){ print(t); cout << '\n'; return 0; } template int out(const Head& head, const Tail&... tail){ print(head); cout << ' '; out(tail...); return 0; } #define CHOOSE(a) CHOOSE2 a #define CHOOSE2(a0,a1,a2,a3,a4,x,...) x #define debug_1(x1) cout<<#x1<<": "< struct Fp { long long val; constexpr Fp(long long v = 0) noexcept : val(v % MOD) { if (val < 0) val += MOD; } constexpr int getmod() { return MOD; } constexpr Fp operator - () const noexcept { return val ? MOD - val : 0; } constexpr Fp operator + (const Fp& r) const noexcept { return Fp(*this) += r; } constexpr Fp operator - (const Fp& r) const noexcept { return Fp(*this) -= r; } constexpr Fp operator * (const Fp& r) const noexcept { return Fp(*this) *= r; } constexpr Fp operator / (const Fp& r) const noexcept { return Fp(*this) /= r; } constexpr Fp& operator += (const Fp& r) noexcept { val += r.val; if (val >= MOD) val -= MOD; return *this; } constexpr Fp& operator -= (const Fp& r) noexcept { val -= r.val; if (val < 0) val += MOD; return *this; } constexpr Fp& operator *= (const Fp& r) noexcept { val = val * r.val % MOD; return *this; } constexpr Fp& operator /= (const Fp& r) noexcept { long long a = r.val, b = MOD, u = 1, v = 0; while (b) { long long t = a / b; a -= t * b; swap(a, b); u -= t * v; swap(u, v); } val = val * u % MOD; if (val < 0) val += MOD; return *this; } constexpr bool operator == (const Fp& r) const noexcept { return this->val == r.val; } constexpr bool operator != (const Fp& r) const noexcept { return this->val != r.val; } friend constexpr ostream& operator << (ostream &os, const Fp& x) noexcept { return os << x.val; } friend constexpr istream& operator >> (istream &is, Fp& x) noexcept { return is >> x.val; } friend constexpr Fp modpow(const Fp &a, long long n) noexcept { if (n == 0) return 1; auto t = modpow(a, n / 2); t = t * t; if (n & 1) t = t * a; return t; } }; // 二項係数ライブラリ template struct BiCoef { vector fact_, inv_, finv_; constexpr BiCoef() {} constexpr BiCoef(int n) noexcept : fact_(n, 1), inv_(n, 1), finv_(n, 1) { init(n); } constexpr void init(int n) noexcept { fact_.assign(n, 1), inv_.assign(n, 1), finv_.assign(n, 1); int MOD = fact_[0].getmod(); for(int i = 2; i < n; i++){ fact_[i] = fact_[i-1] * i; inv_[i] = -inv_[MOD%i] * (MOD/i); finv_[i] = finv_[i-1] * inv_[i]; } } constexpr T com(int n, int k) const noexcept { if(n == k) return 1; if (n < k || n < 0 || k < 0) return 0; return fact_[n] * finv_[k] * finv_[n-k]; } constexpr T fact(int n) const noexcept { if (n < 0) return 0; return fact_[n]; } constexpr T inv(int n) const noexcept { if (n < 0) return 0; return inv_[n]; } constexpr T finv(int n) const noexcept { if (n < 0) return 0; return finv_[n]; } }; //const int MOD = 1000000007; const int MOD = 998244353; using mint = Fp; BiCoef bc; struct UnionFind { vector par, w; UnionFind(int n) : par(n, -1), w(n, 0) { } void init(int n) { par.assign(n, -1); w.assign(n, 0); } int root(int x) { if (par[x] < 0) return x; else return par[x] = root(par[x]); } bool issame(int x, int y) { return root(x) == root(y); } bool merge(int x, int y) { x = root(x); y = root(y); if (x == y) { ++w[x]; return false; } if (par[x] > par[y]) swap(x, y); // merge technique par[x] += par[y]; par[y] = x; w[x] += w[y]; ++w[x]; return true; } int size(int x) { return -par[root(x)]; } int wei(int x) { return w[root(x)]; } }; mint dp[5050][5050][2]; mint sdp[5050][5050]; void solve() { INT(n, m); VEC(int, p, n); vec(int, deg, n, 0); vvc g(n, vc()); UnionFind uf(n); int cnt2 = n; rep(i, n) { -- p[i]; ++ deg[i], ++ deg[p[i]]; g[i].pb(p[i]); g[p[i]].pb(i); if(uf.merge(i, p[i])) -- cnt2; } queue que; vc used(n, 0); rep(i, n) if(deg[i] == 1) que.push(i); int cnt = n; while(que.size()) { int v = que.front(); que.pop(); used[v] = 1; -- cnt; for(int nv: g[v]) { if(deg[nv] > 1) { -- deg[nv]; if(deg[nv] == 1) { que.push(nv); } } } } debug(cnt, cnt2); // cnt個で構成された閉路 rep(i, 5050) rep(j, 5050) rep(k, 2) dp[i][j][k] = 0; rep(i, 5050) rep(j, 5050) sdp[i][j] = 0; // dp[1][1][1] = 1; // for(int i = 1; i <= cnt; ++ i) { // for(int j = 1; j <= i; ++ j) { // dp[i + 1][j + 1][0] += dp[i][j][0] + dp[i][j][1]; // dp[i + 1][j][1] += dp[i][j][0]; // dp[i + 1][j][0] += dp[i][j][1] * (j - 1); // if(j >= 2) dp[i + 1][j][0] += dp[i][j][0] * (j - 2); // } // } // for(int j = 1; j <= cnt; ++ j) { // sdp[cnt][j] = dp[cnt][j][0]; // } int cnt3 = 0; auto dfs = [&](auto &&self, int v) -> void { used[v] = 1; ++ cnt3; for(int nv: g[v]) { if(!used[nv]) self(self, nv); } }; int cur = 0; sdp[0][0] = 1; rep(v, n) { if(!used[v]) { cnt3 = 0; dfs(dfs, v); debug(cnt3, cur); // cnt3個ののloop for(int j = 0; j <= cur; ++ j) { dp[cur + 1][j][1] += sdp[cur][j] * j; dp[cur + 1][j + 1][1] += sdp[cur][j]; } // for(int i = 1; i < cnt3; ++ i) { for(int j = 0; j <= cur + i; ++ j) { dp[cur + i + 1][j + 1][0] += dp[cur + i][j][0] + dp[cur + i][j][1]; dp[cur + i + 1][j][1] += dp[cur + i][j][0]; dp[cur + i + 1][j][0] += dp[cur + i][j][1] * (j - 1); if(j >= 2) dp[cur + i + 1][j][0] += dp[cur + i][j][0] * (j - 2); } } // cur += cnt3; for(int j = 0; j <= cur; ++ j) { sdp[cur][j] = dp[cur][j][0]; //debug(sdp[cur][j]); } } } debug(cur); // n - cnt個で構成された木の部分 for(int i = cnt; i < n; ++ i) { for(int j = 0; j <= i; ++ j) { sdp[i + 1][j + 1] += sdp[i][j]; sdp[i + 1][j] += sdp[i][j] * (j - 1); } } out(sdp[n][m]); } signed main() { ios::sync_with_stdio(false); cin.tie(0); // cout << fixed << setprecision(20); // INT(t); rep(i, t)solve(); solve(); return 0; }