#include <cstdio>
#include <vector>
#include <queue>

using namespace std;

struct E {
  int to;
  int cap;
  int cost;
};

const int N = 350 + 7;
const int INF = (int) 2e9;
int dist[N];
int par[N];
int n;
int m;
int s;
int d;
vector<E> e;
vector<int> g[N];

void add(int x, int y, int c, int z) {
  g[x].push_back((int) e.size());
  g[y].push_back((int) e.size() + 1);
  e.push_back({y, c, z});
  e.push_back({x, 0, -z});
}

struct T {
  int x;
  int val;
};

bool operator < (T a, T b) {
  return a.val > b.val;
}

pair<int, int> get() {
  int sol = 0;
  int cost = 0;
  while (1) {
    for (int i = 1; i <= n; i++) {
      dist[i] = INF;
      par[i] = -1;
    }
    priority_queue<T> q;
    q.push({s, 0});
    dist[s] = 0;
    while (!q.empty()) {
      T k = q.top();
      q.pop();
      int x = k.x;
      if (k.val != dist[x]) {
        continue;
      }
      for (auto &i : g[x]) {
        if (e[i].cap > 0) {
          int y = e[i].to;
          int dnew = dist[x] + e[i].cap;
          if (dnew < dist[y]) {
            dist[y] = dnew;
            par[y] = i;
            q.push({y, dist[y]});
          }
        }
      }
    }
    if (par[d] == -1) {
      break;
    }
    vector<int> ids;
    int node = d;
    while (node != s) {
      int i = par[node] ^ 1;
      ids.push_back(i ^ 1);
      node = e[i].to;
    }
    int vmin = INF, sum = 0;
    for (auto &i : ids) {
      vmin = min(vmin, e[i].cap);
      sum += e[i].cost;
    }
    sol += vmin;
    cost += sum * vmin;
    for (auto &i : ids) {
      e[i].cap -= vmin;
      e[i ^ 1].cap += vmin;
    }
  }
  return make_pair(sol, cost);
}

int main() {
  freopen ("fmcm.in", "r", stdin);
  freopen ("fmcm.out", "w", stdout);

  scanf("%d %d %d %d", &n, &m, &s, &d);
  for (int i = 1; i <= m; i++) {
    int x, y, c, z;
    scanf("%d %d %d %d", &x, &y, &c, &z);
    add(x, y, c, z);
  }
  pair<int, int> x = get();
  printf("%d\n", x.second);
}