#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 Edge { int src, dst; CostType cost; Edge(int src, int dst, CostType cost = 0) : src(src), dst(dst), cost(cost) {} inline bool operator<(const Edge &x) const { return cost != x.cost ? cost < x.cost : dst != x.dst ? dst < x.dst : src < x.src; } inline bool operator<=(const Edge &x) const { return !(x < *this); } inline bool operator>(const Edge &x) const { return x < *this; } inline bool operator>=(const Edge &x) const { return !(*this < x); } }; template struct Dijkstra { Dijkstra(const std::vector>> &graph, const CostType CINF) : graph(graph), CINF(CINF) {} std::vector build(int s) { is_built = true; int n = graph.size(); std::vector dist(n, CINF); dist[s] = 0; prev.assign(n, -1); using Pci = std::pair; std::priority_queue, std::greater> que; que.emplace(0, s); while (!que.empty()) { CostType cost; int ver; std::tie(cost, ver) = que.top(); que.pop(); if (dist[ver] < cost) continue; for (const Edge &e : graph[ver]) { if (dist[e.dst] > dist[ver] + e.cost) { dist[e.dst] = dist[ver] + e.cost; prev[e.dst] = ver; que.emplace(dist[e.dst], e.dst); } } } return dist; } std::vector build_path(int t) const { assert(is_built); std::vector res; for (; t != -1; t = prev[t]) res.emplace_back(t); std::reverse(res.begin(), res.end()); return res; } private: bool is_built = false; std::vector>> graph; const CostType CINF; std::vector prev; }; int main() { int n, m; cin >> n >> m; vector>> graph(n); map, int> mp; vector d(m); REP(i, m) { int u, v, c; cin >> u >> v >> c >> d[i]; --u; --v; graph[u].emplace_back(u, v, c); graph[v].emplace_back(v, u, c); mp[{u, v}] = i; } Dijkstra dij(graph, LINF); ll ans = dij.build(0)[n - 1]; vector path = dij.build_path(n - 1); for (int i = 0; i + 1 < path.size(); ++i) { int u = path[i], v = path[i + 1]; if (u > v) swap(u, v); for (auto &e : graph[u]) { if (e.dst == v) e.cost = d[mp[{u, v}]]; } for (auto &e : graph[v]) { if (e.dst == u) e.cost = d[mp[{u, v}]]; } } cout << ans + Dijkstra(graph, LINF).build(0)[n - 1] << '\n'; return 0; }