#include <cstdio>
#include <cstdlib>
#include <algorithm>
#include <vector>
#include <queue>
#include <map>
#include <set>
using namespace std;

const int nmax = 355;
const int inf = 0x3f3f3f3f;

struct Edge {
    int u, v, cap, flow, ind, cost;
    Edge(int _u, int _v, int _cap, int _flow, int _ind, int _cost) {
        u = _u;
        v = _v;
        cap = _cap;
        flow = _flow;
        ind = _ind;
        cost = _cost;
    }
};

vector<Edge> E;
vector<int> g[nmax];
int n, m, k, source, sink;
int father[nmax], dist[nmax];
bool inqueue[nmax];
vector<vector<int> > ans;
long long total;

bool bellmanford() {
    for (int i = 1; i <= n; ++ i) {
        inqueue[i] = 0;
        father[i] = -1;
        dist[i] = 2000000001;
    }
    queue<int> q;
    q.push(source);
    dist[source] = 0;
    inqueue[source] = 1;

    while (!q.empty()) {
        int node = q.front();
        q.pop();
        inqueue[node] = 0;
        for (int ind : g[node]) {
            Edge e = E[ind];
            if (e.cap > e.flow && dist[e.u] + e.cost < dist[e.v]) {
                dist[e.v] = dist[e.u] + e.cost;
                father[e.v] = ind;
                if (!inqueue[e.v]) {
                    inqueue[e.v] = 1;
                    q.push(e.v);
                }
            }
        }
    }
    return dist[sink] != 2000000001;
}

void maxflow() {
    long long flow = 0;
    while (true) {
        if (!bellmanford()) {
            break;
        }
        int minflow = inf, node = sink;
        while (node != source) {
            Edge e = E[father[node]];
            minflow = min(minflow, e.cap - e.flow);
            node = e.u;
        }
        node = sink;
        while (node != source) {
            Edge &e = E[father[node]];
            Edge &re = E[father[node] ^ 1];

            e.flow += minflow;
            re.flow -= minflow;
            node = e.u;
        }
        total += minflow * dist[sink];
        flow += minflow;
    }
    printf("%lld\n", total);
}

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

    scanf("%i %i %i %i", &n, &m, &source, &sink);

    for (int i = 1; i <= m; ++ i) {
        int x, y, c, z;
        scanf("%i %i %i %i", &x, &y, &c, &z);
        E.push_back(Edge(x, y, c, 0, i, z));
        g[x].push_back(E.size() - 1);
        E.push_back(Edge(y, x, 0, 0, i, -z));
        g[y].push_back(E.size() - 1);
    }
    maxflow();
    return 0;
}