#include <bits/stdc++.h>
using namespace std;

#define NMAX 350
#define INF INT_MAX

struct Edge {
    int from, to, capacity, cost, flow;
};

vector<Edge> edges;
vector<int> adj[NMAX];
int dist[NMAX], parent[NMAX], parentEdge[NMAX], potential[NMAX];
bool inQueue[NMAX];

void addEdge(int from, int to, int capacity, int cost) {
    edges.push_back({from, to, capacity, cost, 0});
    edges.push_back({to, from, 0, -cost, 0});
    adj[from].push_back(edges.size() - 2);
    adj[to].push_back(edges.size() - 1);
}

bool bellmanFord(int source, int n) {
    fill(dist, dist + n, INF);
    dist[source] = 0;
    queue<int> q;
    q.push(source);
    inQueue[source] = true;

    while (!q.empty()) {
        int u = q.front();
        q.pop();
        inQueue[u] = false;

        for (int idx : adj[u]) {
            Edge& e = edges[idx];
            if (e.flow < e.capacity && dist[u] + e.cost < dist[e.to]) {
                dist[e.to] = dist[u] + e.cost;
                if (!inQueue[e.to]) {
                    q.push(e.to);
                    inQueue[e.to] = true;
                }
            }
        }
    }
    for (int i = 0; i < n; ++i) {
        potential[i] = (dist[i] == INF) ? 0 : dist[i];
    }
    return true;
}

bool dijkstra(int source, int sink, int n) {
    fill(dist, dist + n, INF);
    fill(parent, parent + n, -1);
    fill(parentEdge, parentEdge + n, -1);
    dist[source] = 0;
    priority_queue<pair<int, int>, vector<pair<int, int>>, greater<pair<int, int>>> pq;
    pq.push({0, source});

    while (!pq.empty()) {
        int d = pq.top().first;
        int u = pq.top().second;
        pq.pop();

        if (d != dist[u]) continue;

        for (int idx : adj[u]) {
            Edge& e = edges[idx];
            int v = e.to;
            int newDist = dist[u] + e.cost + potential[u] - potential[v];
            if (e.flow < e.capacity && newDist < dist[v]) {
                dist[v] = newDist;
                parent[v] = u;
                parentEdge[v] = idx;
                pq.push({newDist, v});
            }
        }
    }
    for (int i = 0; i < n; ++i) {
        if (dist[i] < INF) potential[i] += dist[i];
    }
    return parent[sink] != -1;
}

int minCostMaxFlow(int source, int sink, int n) {
    int flow = 0, cost = 0;
    bellmanFord(source, n);

    while (dijkstra(source, sink, n)) {
        int pathFlow = INF;
        for (int v = sink; v != source; v = parent[v]) {
            int idx = parentEdge[v];
            pathFlow = min(pathFlow, edges[idx].capacity - edges[idx].flow);
        }
        for (int v = sink; v != source; v = parent[v]) {
            int idx = parentEdge[v];
            edges[idx].flow += pathFlow;
            edges[idx ^ 1].flow -= pathFlow;
            cost += pathFlow * edges[idx].cost;
        }
        flow += pathFlow;
    }
    return cost;
}

int main() {
    ifstream fin("fmcm.in");
    ofstream fout("fmcm.out");

    int n, m, s, d;
    fin >> n >> m >> s >> d;
    for (int i = 0; i < m; ++i) {
        int u, v, c, z;
        fin >> u >> v >> c >> z;
        addEdge(u, v, c, z);
    }
    fin.close();

    int result = minCostMaxFlow(s, d, n + 1);
    fout << result << '\n';
    fout.close();

    return 0;
}