#include #include using namespace std; using namespace atcoder; //using mint = modint1000000007; //const int mod = 1000000007; //using mint = modint998244353; //const int mod = 998244353; //const int INF = 1e9; //const long long LINF = 1e18; #define rep(i, n) for (int i = 0; i < (n); ++i) #define rep2(i,l,r)for(int i=(l);i<(r);++i) #define rrep(i, n) for (int i = (n-1); i >= 0; --i) #define rrep2(i,l,r)for(int i=(r-1);i>=(l);--i) #define all(x) (x).begin(),(x).end() #define allR(x) (x).rbegin(),(x).rend() #define endl "\n" #define P pair template inline bool chmax(A & a, const B & b) { if (a < b) { a = b; return true; } return false; } template inline bool chmin(A & a, const B & b) { if (a > b) { a = b; return true; } return false; } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); int n, m; cin >> n >> m; scc_graph ss(n); vectora(m), b(m); rep(i, m) { cin >> a[i] >> b[i]; a[i]--, b[i]--; ss.add_edge(a[i], b[i]); } auto vv = ss.scc(); if (1 == vv.size()) { cout << 0 << endl; return 0; } dsu uf(n); int sz = vv.size(); for (auto & v : vv) { auto top = v[0]; for (auto e : v) uf.merge(e, top); } setin, out; rep(i, m) { int l0 = uf.leader(a[i]); int l1 = uf.leader(b[i]); if (l0 == l1)continue; in.insert(l0); out.insert(l1); } int ans = sz - min(in.size(), out.size()); cout << ans << endl; return 0; }