#define _USE_MATH_DEFINES #include using namespace std; #define FOR(i,m,n) for(int i=(m);i<(n);++i) #define REP(i,n) FOR(i,0,n) #define ALL(v) (v).begin(),(v).end() using ll = long long; constexpr int INF = 0x3f3f3f3f; constexpr long long LINF = 0x3f3f3f3f3f3f3f3fLL; constexpr double EPS = 1e-8; constexpr int MOD = 1000000007; // constexpr int MOD = 998244353; constexpr int dy[] = {1, 0, -1, 0}, dx[] = {0, -1, 0, 1}; constexpr int dy8[] = {1, 1, 0, -1, -1, -1, 0, 1}, dx8[] = {0, -1, -1, -1, 0, 1, 1, 1}; template inline bool chmax(T &a, U b) { return a < b ? (a = b, true) : false; } template inline bool chmin(T &a, U b) { return a > b ? (a = b, true) : false; } struct IOSetup { IOSetup() { std::cin.tie(nullptr); std::ios_base::sync_with_stdio(false); std::cout << fixed << setprecision(20); } } iosetup; template struct PrimalDual2 { struct Edge { int dst, rev; T cap; U cost; Edge(int dst, T cap, U cost, int rev) : dst(dst), cap(cap), cost(cost), rev(rev) {} }; std::vector> graph; PrimalDual2(int n, const T TINF, const U UINF) : n(n), UINF(UINF), graph(n + 2), d(n + 2, 0) {} void add_edge(int src, int dst, T cap, U cost) { if (cost < 0) { d[src] -= cap; d[dst] += cap; res += cost * cap; std::swap(src, dst); cost = -cost; } graph[src].emplace_back(dst, cap, cost, graph[dst].size()); graph[dst].emplace_back(src, 0, -cost, graph[src].size() - 1); } U minimum_cost_flow() { T flow = 0; for (int i = 0; i < n; ++i) { if (d[i] > 0) { add_edge(n, i, d[i], 0); flow += d[i]; } else if (d[i] < 0) { add_edge(i, n + 1, -d[i], 0); } } std::vector prev_v(n + 2, -1), prev_e(n + 2, -1); std::vector potential(n + 2, 0), dist(n + 2); std::priority_queue, std::greater> que; while (flow > 0) { std::fill(dist.begin(), dist.end(), UINF); dist[n] = 0; que.emplace(0, n); while (!que.empty()) { U fst; int ver; std::tie(fst, ver) = que.top(); que.pop(); if (dist[ver] < fst) continue; for (int i = 0; i < graph[ver].size(); ++i) { Edge &e = graph[ver][i]; U nx = dist[ver] + e.cost + potential[ver] - potential[e.dst]; if (e.cap > 0 && dist[e.dst] > nx) { dist[e.dst] = nx; prev_v[e.dst] = ver; prev_e[e.dst] = i; que.emplace(dist[e.dst], e.dst); } } } if (dist[n + 1] == UINF) return UINF; for (int i = 0; i < n + 2; ++i) { if (dist[i] != UINF) potential[i] += dist[i]; } T f = flow; for (int v = n + 1; v != n; v = prev_v[v]) { if (graph[prev_v[v]][prev_e[v]].cap < f) f = graph[prev_v[v]][prev_e[v]].cap; } flow -= f; res += potential[n + 1] * f; for (int v = n + 1; v != n; v = prev_v[v]) { Edge &e = graph[prev_v[v]][prev_e[v]]; e.cap -= f; graph[v][e.rev].cap += f; } } return res; } U minimum_cost_flow(int s, int t, T flow) { d[s] += flow; d[t] -= flow; return minimum_cost_flow(); } private: using Pui = std::pair; int n; const U UINF; U res = 0; std::vector d; }; int main() { int n, m; cin >> n >> m; PrimalDual2 pd(n, INF, LINF); while (m--) { int u, v, c, d; cin >> u >> v >> c >> d; --u; --v; pd.add_edge(u, v, 1, c); pd.add_edge(v, u, 1, c); pd.add_edge(u, v, 1, d); pd.add_edge(v, u, 1, d); } cout << pd.minimum_cost_flow(0, n - 1, 2) << '\n'; return 0; }