#include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; using Int = long long; template ostream &operator<<(ostream &os, const vector &as); template ostream &operator<<(ostream &os, const pair &a) { return os << "(" << a.first << ", " << a.second << ")"; }; template ostream &operator<<(ostream &os, const vector &as) { const int sz = as.size(); os << "["; for (int i = 0; i < sz; ++i) { if (i >= 256) { os << ", ..."; break; } if (i > 0) { os << ", "; } os << as[i]; } return os << "]"; } template void pv(T a, T b) { for (T i = a; i != b; ++i) cerr << *i << " "; cerr << endl; } template bool chmin(T &t, const T &f) { if (t > f) { t = f; return true; } return false; } template bool chmax(T &t, const T &f) { if (t < f) { t = f; return true; } return false; } #define COLOR(s) ("\x1b[" s "m") struct Scc { int n; vector as, bs; vector ptr, zu, us; int l; vector ids; int operator[](int u) const { return ids[u]; } Scc() {} explicit Scc(int n_) : n(n_), as(), bs(), l(-1) {} void ae(int u, int v) { assert(0 <= u); assert(u < n); assert(0 <= v); assert(v < n); as.push_back(u); bs.push_back(v); } void dfs0(int u) { if (!ids[u]) { ids[u] = -1; for (int i = ptr[u]; i < ptr[u + 1]; ++i) dfs0(zu[i]); us.push_back(u); } } void dfs1(int u) { if (!~ids[u]) { ids[u] = l; for (int i = ptr[u]; i < ptr[u + 1]; ++i) dfs1(zu[i]); } } void run() { const int m = as.size(); ptr.resize(n + 2); zu.resize(m); for (int u = 0; u < n + 2; ++u) ptr[u] = 0; for (int i = 0; i < m; ++i) ++ptr[as[i] + 2]; for (int u = 2; u < n + 1; ++u) ptr[u + 1] += ptr[u]; for (int i = 0; i < m; ++i) zu[ptr[as[i] + 1]++] = bs[i]; ids.assign(n, 0); us.clear(); for (int u = 0; u < n; ++u) dfs0(u); for (int u = 0; u < n + 2; ++u) ptr[u] = 0; for (int i = 0; i < m; ++i) ++ptr[bs[i] + 2]; for (int u = 2; u < n + 1; ++u) ptr[u + 1] += ptr[u]; for (int i = 0; i < m; ++i) zu[ptr[bs[i] + 1]++] = as[i]; l = 0; for (int j = n; --j >= 0; ) if (!~ids[us[j]]) { dfs1(us[j]); ++l; } } vector> group() const { assert(~l); vector> uss(l); for (int u = 0; u < n; ++u) uss[ids[u]].push_back(u); return uss; } }; // Scc int N, M; vector A, B, C; vector>> graph0, graph1; vector vis, fs; bool dfs(int u, int f) { if (vis[u]) return (fs[u] == f); vis[u] = 1; fs[u] = f; for (const auto &e : graph0[u]) { const int ff = f + e.first; const int v = e.second; if (!dfs(v, ff)) return false; } return true; } int main() { for (; ~scanf("%d%d", &N, &M); ) { A.resize(M); B.resize(M); C.resize(M); for (int i = 0; i < M; ++i) { scanf("%d%d%d", &A[i], &B[i], &C[i]); --A[i]; --B[i]; } const int n = N + N; Scc scc(n); vector as, bs, cs; auto ae = [&](int u, int v, int c) -> void { // cerr<