#include #define inf (long long)(1e17) using namespace std; template struct Primal_Dual { using Pa = pair; long long infinity = inf; struct edge { int to; T cap, cost; int rev; }; int v; vector> edges; vector h; vector dist; vector prevv, preve; Primal_Dual(int vsize = 1) { v = vsize; edges.resize(v); h.resize(v); dist.resize(v); prevv.resize(v); preve.resize(v); } bool add(int from, int to, T cap, T cost) { edges[from].push_back((edge){to, cap, cost, (int)edges[to].size()}); edges[to].push_back((edge){from, 0, -cost, (int)edges[from].size() - 1}); return 1; } T solve(int s, int t, T f) { T ans = 0; h.assign(v, 0); while (f > 0) { priority_queue, greater> qu; dist.assign(v, infinity); dist[s] = 0; qu.push({0, s}); while (!qu.empty()) { Pa now = qu.top(); qu.pop(); int nowv = now.second; if (dist[nowv] < now.first) continue; for (int i = 0; i < (int)edges[nowv].size(); ++i) { edge &e = edges[nowv][i]; if (e.cap > 0 && dist[e.to] > dist[nowv] + e.cost + h[nowv] - h[e.to]) { dist[e.to] = dist[nowv] + e.cost + h[nowv] - h[e.to]; prevv[e.to] = nowv; preve[e.to] = i; qu.push({dist[e.to], e.to}); } } } if (dist[t] == infinity) return -1; for (int i = 0; i < v; ++i) h[i] += dist[i]; T d = f; for (int i = t; i != s; i = prevv[i]) d = min(d, edges[prevv[i]][preve[i]].cap); f -= d; ans += d * h[t]; for (int i = t; i != s; i = prevv[i]) { edge &e = edges[prevv[i]][preve[i]]; e.cap -= d; edges[i][e.rev].cap += d; } } return ans; } }; using P = pair; int n, m; Primal_Dual pd; int main() { cin >> n >> m; pd = Primal_Dual(n); for (int i = 0; i < m; ++i) { int x, y, c, d; cin >> x >> y >> c >> d; pd.add(--x, --y, 1, c); pd.add(y, x, 1, c); pd.add(x, y, 1, d); pd.add(y, x, 1, d); } cout << pd.solve(0, n - 1, 2) << endl; return 0; }