#include #ifdef LOCAL #include #else #define debug(...) void(0) #endif struct UnionFind { UnionFind(int n) : n(n), num(n), data(n, -1) {} int find(int x) { assert(0 <= x && x < n); return data[x] < 0 ? x : data[x] = find(data[x]); } bool merge(int x, int y) { assert(0 <= x && x < n); assert(0 <= y && y < n); if ((x = find(x)) == (y = find(y))) return false; if (-data[x] < -data[y]) std::swap(x, y); data[x] += data[y]; data[y] = x; num--; return true; } bool same(int x, int y) { assert(0 <= x && x < n); assert(0 <= y && y < n); return find(x) == find(y); } int size(int x) { assert(0 <= x && x < n); return -data[find(x)]; } int count() const { return num; } std::vector> groups() { std::vector> res(n); for (int i = 0; i < n; i++) res[find(i)].emplace_back(i); res.erase(std::remove_if(res.begin(), res.end(), [&](const std::vector& v) { return v.empty(); })); return res; } int operator[](int x) { return find(x); } private: int n, num; // root node : -1 * component size // otherwise : parent std::vector data; }; using namespace std; typedef long long ll; #define all(x) begin(x), end(x) constexpr int INF = (1 << 30) - 1; constexpr long long IINF = (1LL << 60) - 1; constexpr int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1}; template istream& operator>>(istream& is, vector& v) { for (auto& x : v) is >> x; return is; } template ostream& operator<<(ostream& os, const vector& v) { auto sep = ""; for (const auto& x : v) os << exchange(sep, " ") << x; return os; } template bool chmin(T& x, U&& y) { return y < x and (x = forward(y), true); } template bool chmax(T& x, U&& y) { return x < y and (x = forward(y), true); } template void mkuni(vector& v) { sort(begin(v), end(v)); v.erase(unique(begin(v), end(v)), end(v)); } template int lwb(const vector& v, const T& x) { return lower_bound(begin(v), end(v), x) - begin(v); } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); int N, M; cin >> N >> M; vector deg(N, 0); UnionFind uf(N); for (; M--;) { int U, V; cin >> U >> V; deg[--U]++; deg[--V]--; uf.merge(U, V); } vector sum(N, 0); for (int i = 0; i < N; i++) sum[uf[i]] += max(0, deg[i]); int cnt = 0, nonzero = 0, ans = 0; for (int i = 0; i < N; i++) { if (i != uf[i]) continue; cnt += (uf.size(i) > 1); nonzero += (sum[i] != 0); ans += sum[i]; } if (cnt == 1) ans = max(0, ans - 1); else ans += cnt - 1 - nonzero; cout << ans << '\n'; return 0; }