//#define NDEBUG #pragma warning(disable : 4146) #include namespace n91 { using i32 = std::int32_t; using i64 = std::int64_t; using u32 = std::uint32_t; using u64 = std::uint64_t; using isize = std::ptrdiff_t; using usize = std::size_t; using f64 = double; struct rep { struct itr { usize i; constexpr itr(const usize i) noexcept : i(i) {} void operator++() noexcept { ++i; } constexpr usize operator*() const noexcept { return i; } constexpr bool operator!=(const itr x) const noexcept { return i != x.i; } }; const itr f, l; constexpr rep(const usize f, const usize l) noexcept : f(std::min(f, l)), l(l) {} constexpr auto begin() const noexcept { return f; } constexpr auto end() const noexcept { return l; } }; struct revrep { struct itr { usize i; constexpr itr(const usize i) noexcept : i(i) {} void operator++() noexcept { --i; } constexpr usize operator*() const noexcept { return i; } constexpr bool operator!=(const itr x) const noexcept { return i != x.i; } }; const itr f, l; constexpr revrep(const usize f, const usize l) noexcept : f(l - 1), l(std::min(f, l) - 1) {} constexpr auto begin() const noexcept { return f; } constexpr auto end() const noexcept { return l; } }; template auto md_vec(const usize n, const T &value) { return std::vector(n, value); } template auto md_vec(const usize n, Args... args) { return std::vector(n, md_vec(args...)); } template constexpr T difference(const T &a, const T &b) noexcept { return a < b ? b - a : a - b; } template void chmin(T &a, const T &b) noexcept { if (b < a) a = b; } template void chmax(T &a, const T &b) noexcept { if (a < b) a = b; } template class rec_lambda { F f; public: rec_lambda(F &&f_) : f(std::forward(f_)) {} template auto operator()(Args &&... args) const { return f(*this, std::forward(args)...); } }; template T scan() { T ret; std::cin >> ret; return ret; } constexpr char eoln = '\n'; i64 floor_div(const i64 n, const i64 d) { assert(d != 0); return n / d - static_cast((n ^ d) < 0 && n % d != 0); } i64 ceil_div(const i64 n, const i64 d) { assert(d != 0); return n / d + static_cast((n ^ d) >= 0 && n % d != 0); } #ifdef N91_LOCAL #define OJ_LOCAL(a, b) b #else #define OJ_LOCAL(a, b) a #endif } // namespace n91 #include using mint = atcoder::modint998244353; struct dsu { std::vector p; dsu(int n) : p(n, -1) {} int find(int i) { return p[i] == -1 ? i : p[i] = find(p[i]); } void merge(int x, int y) { x = find(x); y = find(y); p[y] = x; } }; namespace n91 { struct arcset { mint add; std::set st; }; void main_() { const usize n = scan(); const usize m = scan(); auto g = md_vec(n, 0, usize()); std::vector as(n); for (const usize i : rep(0, m)) { const usize u = scan() - 1; const usize v = scan() - 1; g[v].push_back(u); as[u].st.insert(v); } dsu uf(n); std::vector dp(n); for (const usize v : rep(0, n)) { dp[v] += 1; for (const usize u : g[v]) { const usize x = uf.find(u); if (x == v) continue; uf.merge(v, x); if (as[x].st.erase(v)) dp[v] += as[x].add; if (as[v].st.size() < as[x].st.size()) std::swap(as[v], as[x]); for (const usize t : as[x].st) { dp[t] += as[x].add; if (as[v].st.insert(t).second) dp[t] -= as[v].add; } as[x].st.clear(); } as[v].add += dp[v]; } std::cout << std::accumulate(dp.begin(), dp.end(), mint(0)).val() << eoln; } } // namespace n91 int main() { //* std::ios::sync_with_stdio(false); std::cin.tie(nullptr); //*/ std::cout << std::fixed << std::setprecision(20); n91::main_(); return 0; }