import heapq import sys input = sys.stdin.buffer.readline sys.setrecursionlimit(10 ** 7) class MCF_graph(object): def __init__(self, n): self.n = n self.g = [[] for _ in range(n)] # to, rev, cap, cost self.pos = [] def add_edge(self, frm, to, cap, cost): m = len(self.pos) self.pos.append((frm, len(self.g[frm]))) self.g[frm].append([to, len(self.g[to]), cap, cost]) self.g[to].append([frm, len(self.g[frm]) - 1, 0, -cost]) return m def __get_edge(self, i): e_to, e_rev, e_cap, e_cost = self.g[self.pos[i][0]][self.pos[i][1]] re_to, _, re_cap, _ = self.g[e_to][e_rev] # from, to, cap, flow, cost return (re_to, e_to, e_cap + re_cap, re_cap, e_cost) def edges(self): m = len(self.pos) for i in range(m): yield self.__get_edge(i) def flow(self, s, t, flow_limit=10**18): return self.slope(s, t, flow_limit)[-1] def slope(self, s, t, flow_limit=10**18): dual = [0] * self.n flow = 0 cost = 0 prev_cost = -1 result = [(0, 0)] # cap, cost while flow < flow_limit: # call dual_ref() dist = [10**18] * self.n pv = [-1] * self.n pe = [-1] * self.n vis = [False] * self.n dist[s] = 0 que = [(0, s)] while que: _, v = heapq.heappop(que) if vis[v]: continue vis[v] = True if v == t: break for i, (e_to, _, e_cap, e_cost) in enumerate(self.g[v]): if vis[e_to] or (not e_cap): continue tmp_cost = e_cost - dual[e_to] + dual[v] if dist[e_to] > dist[v] + tmp_cost: dist[e_to] = dist[v] + tmp_cost pv[e_to] = v pe[e_to] = i heapq.heappush(que, (dist[e_to], e_to)) if not vis[t]: break for v, visited in enumerate(vis): if not visited: continue dual[v] -= dist[t] - dist[v] # end dual_ref() c = flow_limit - flow v = t while v != s: c = min(c, self.g[pv[v]][pe[v]][2]) v = pv[v] v = t while v != s: i, j = pv[v], pe[v] self.g[i][j][2] -= c self.g[v][self.g[i][j][1]][2] += c v = i d = -dual[s] flow += c cost += c * d if prev_cost == d: result.pop() result.append((flow, cost)) prev_cost = cost return result n, m = map(int, input().split()) g = MCF_graph(n) for _ in range(m): a, b, c, d = map(int, input().split()) a -= 1 b -= 1 g.add_edge(a, b, 1, c) g.add_edge(a, b, 1, d) g.add_edge(b, a, 1, c) g.add_edge(b, a, 1, d) res = g.flow(0, n - 1, 2)[-1] print(res)