//#pragma GCC optimize("Ofast")
//#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,tune=native")
#include <iostream>
#include <fstream>
#include <cassert>
#include <vector>
#include <functional>

using namespace std;

template <
  typename CapType, typename TotalCapType, 
  typename CostType, typename TotalCostType
>
class CostScaling {
private:
  static const int alpha = 8; // eps <- max(1, eps / alpha)

  using cap_t = CapType;
  using tcap_t = TotalCapType;
  using cost_t = CostType; // > max{|C|} * (2 * |V|)
  using tcost_t = TotalCostType;
  static constexpr cost_t Inf = (tcap_t(1) << (sizeof(tcap_t) * 8 - 2)) - 1;

  struct InputEdge { int from, to; cap_t b, c; cost_t cost; };
  struct Edge { int to, rev; cap_t cap; cost_t cost; };

  class Dinic {
  public:
    Dinic(int N, const vector<int>& ofs, vector<Edge>& edges, 
        vector<tcap_t>& capacity) 
      : N(N), ofs(ofs), edges(edges), capacity(capacity), last(N) {}

    bool succeeded() {
      // s -> u: capacity[u]
      // u -> t: capacity[u + N]
      tcap_t f = 0;
      for (int u = 0; u < N; ++u) f += capacity[u];
      vector<int> que(N);
      while (f) {
        dist.assign(N, -1);
        int qh = 0, qt = 0, lv = N;
        for (int u = 0; u < N; ++u) if (capacity[u] > 0) que[qt++] = u, dist[u] = 0;
        for (; qh < qt; ) {
          int u = que[qh++];
          if (lv == N && capacity[u + N] > 0) lv = dist[u];
          if (dist[u] > lv) break;
          for (int ei = ofs[u]; ei < ofs[u + 1]; ++ei) {
            int v = edges[ei].to;
            if (edges[ei].cap > 0 && dist[v] == -1) {
              que[qt++] = v, dist[v] = dist[u] + 1;
            }
          }
        }
        if (lv == N) break;
        for (int u = 0; u < N; ++u) last[u] = ofs[u];
        for (int u = 0; u < N; ++u) if (capacity[u] > 0) {
          auto df = block_flow(u, capacity[u]);
          f -= df, capacity[u] -= df;
        }
      }
      return f == 0;
    }

  private:
    tcap_t block_flow(int u, tcap_t f) {
      tcap_t ret = 0;
      if (capacity[u + N] > 0) {
        tcap_t df = min(f, capacity[u + N]);
        capacity[u + N] -= df;
        return df;
      }
      for (auto& ei = last[u]; ei < ofs[u + 1]; ++ei) {
        auto& e = edges[ei]; int v = e.to;
        if (e.cap == 0 || dist[v] <= dist[u]) continue;
        cap_t df = block_flow(v, min<cap_t>(e.cap, f));
        if (df == 0) continue;
        e.cap -= df, edges[e.rev].cap += df;
        f -= df, ret += df;
        if (f == 0) break;
      }
      return ret;
    }

    int N;
    const vector<int>& ofs;
    vector<Edge>& edges;
    vector<tcap_t>& capacity;
    vector<int> last, dist;
  };

public:
  CostScaling(int N, int M=0) : N(N), capacity(2 * N) {
    if (M > 0) in.reserve(M);
  }

  void add_directed_edge(int u, int v, cap_t b, cap_t c, cost_t cost) {
    if (b > 0) capacity[v] += b, capacity[u + N] += b;
    else capacity[u] += -b, capacity[v + N] += -b;
    in.push_back({u, v, b, c, cost});
  }

  pair<bool, tcost_t> minimum_cost_circulation() {
    construct();
    if (!has_feasible_circulation()) return {false, 0};

    const int cost_multiplier = 2 << __lg(N); // should be > |V|
    cost_t eps = 0;
    for (auto& e : edges) e.cost *= cost_multiplier, eps = max(eps, e.cost);
    
    while (eps > 1) refine(eps = max<cost_t>(1, eps / alpha));

    tcost_t ret = initial_cost;
    for (auto& e : edges) ret -= (e.cost / cost_multiplier) * e.cap;
    return {true, ret / 2};
  }

private:
  void refine(const cost_t eps) {
    auto cost_p = [&] (int u, const Edge& e) {
      return e.cost + potential[u] - potential[e.to];
    };
    for (int u = 0; u < N; ++u) for (int i = ofs[u]; i < ofs[u + 1]; ++i) {
      auto& e = edges[i];
      if (cost_p(u, e) < 0) edges[e.rev].cap += e.cap, e.cap = 0;
    }
    vector<tcap_t> excess(initial_excess);
    for (auto& e : edges) excess[e.to] -= e.cap;

    vector<int> stack; stack.reserve(N);
    for (int u = 0; u < N; ++u) if (excess[u] > 0) stack.push_back(u);

    auto residue = [&] (const Edge& e) -> cap_t { return e.cap; };
    auto push = [&] (int u, Edge& e, cap_t df) {
      e.cap -= df; edges[e.rev].cap += df;
      excess[e.to] += df; excess[u] -= df;
      if (excess[e.to] > 0 && excess[e.to] <= df) {
        stack.push_back(e.to);
      }
    };
    auto relabel = [&] (int u, cost_t delta) {
      potential[u] -= delta + eps;
    };
    auto relabel_in_advance = [&] (int u) {
      if (excess[u] != 0) return false;
      auto delta = Inf;
      for (int ei = ofs[u]; ei < ofs[u + 1]; ++ei) {
        auto& e = edges[ei];
        if (residue(e) == 0) continue;
        if (cost_p(u, e) < 0) return false;
        else delta = min<tcost_t>(delta, cost_p(u, e));
      }
      relabel(u, delta);
      return true;
    };
    auto discharge = [&] (int u) {
      auto delta = Inf;
      for (int ei = ofs[u]; ei < ofs[u + 1]; ++ei) {
        auto& e = edges[ei];
        if (residue(e) == 0) continue;
        if (cost_p(u, e) < 0) {
          if (relabel_in_advance(e.to)) {
            --ei; continue; // modify ei (!)
          }
          cap_t df = min<tcap_t>(excess[u], residue(e));
          push(u, e, df);
          if (!excess[u]) return;
        } else delta = min<tcost_t>(delta, cost_p(u, e));
      }
      relabel(u, delta);
      stack.push_back(u);
    };
    while (!stack.empty()) {
      auto u = stack.back(); stack.pop_back();
      discharge(u);
    }
  }

  void construct() {
    ofs.assign(N + 1, 0);
    edges.resize(2 * in.size());
    initial_excess.assign(N, 0);
    initial_cost = 0;
    potential.assign(N, 0);
    for (auto& e : in) ofs[e.from + 1]++, ofs[e.to + 1]++;
    for (int i = 1; i <= N; ++i) ofs[i] += ofs[i - 1];
    for (auto& e : in) {
      initial_excess[e.to] += e.c;
      initial_excess[e.from] += -e.b;
      initial_cost += tcost_t(e.cost) * (e.c + e.b);
      edges[ofs[e.from]++] = {e.to, ofs[e.to], e.c - e.b, e.cost};
      edges[ofs[e.to]++] = {e.from, ofs[e.from] - 1, 0, -e.cost};
    }
    for (int i = N; i > 0; --i) ofs[i] = ofs[i - 1];
    ofs[0] = 0;
  }

  bool has_feasible_circulation() {
    return Dinic(N, ofs, edges, capacity).succeeded();
  }

private:
  int N; 
  vector<InputEdge> in;
  vector<tcap_t> capacity;

  vector<int> ofs;
  vector<Edge> edges;

  tcost_t initial_cost;
  vector<tcap_t> initial_excess;
  vector<tcost_t> potential;
};
// cap, total_cap, cost * (2 * |V|), total_cost
using MCC = CostScaling<int, int, int, int>;

int main() {
    #ifdef INFOARENA
    ifstream cin("fmcm.in");
    ofstream cout("fmcm.out");
    #endif
    
    int n, m, s, d; cin >> n >> m >> s >> d; s -= 1; d -= 1;
    
    auto max_flow_finder = MCC(n, m);
    vector<tuple<int, int, int, int>> edges(m);
    for (int i = 0; i < m; i += 1) {
        int x, y, c, z; cin >> x >> y >> c >> z; x -= 1; y -= 1;
        edges[i] = make_tuple(x, y, c, z);
        max_flow_finder.add_directed_edge(x, y, 0, c, 0);
    }
    max_flow_finder.add_directed_edge(d, s, 0, (1 << 30), -1);

    const int max_flow = -max_flow_finder.minimum_cost_circulation().second;
    auto mcc = MCC(n, m);
    for (int i = 0; i < m; i += 1) {
        int x, y, c, z; tie(x, y, c, z) = edges[i];
        mcc.add_directed_edge(x, y, 0, c, z);
    }
    mcc.add_directed_edge(d, s, max_flow, max_flow, 0);
    cout << mcc.minimum_cost_circulation().second << endl;
}