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

#define int long long
#define FOR(i, a, b) for (int i = (a), _##i = (b); i <= _##i; ++i)
#define FORD(i, a, b) for (int i = (a), _##i = (b); i >= _##i; --i)
#define REP(i, a) for (int i = 0, _##i = (a); i < _##i; ++i)
#define REPD(i,n) for(int i = (n)-1; i >= 0; --i)

#define DEBUG(X) { cerr << #X << " = " << (X) << endl; }
#define PR(A, n) { cerr << #A << " = "; FOR(_, 1, n) cerr << A[_] << ' '; cerr << endl; }
#define PR0(A, n) { cerr << #A << " = "; REP(_, n) cerr << A[_] << ' '; cerr << endl; }

#define sqr(x) ((x) * (x))
#define ll long long
#define double long double
typedef pair<int, int> II;
#define __builtin_popcount __builtin_popcountll
#define SZ(x) ((int)(x).size())
#define ALL(a) (a).begin(), (a).end()
#define MS(a,x) memset(a, x, sizeof(a))
#define next ackjalscjaowjico
#define prev ajcsoua0wucckjsl
#define y1 alkscj9u20cjeijc
#define left lajcljascjljl
#define right aucouasocjolkjl
#define y0 u9cqu3jioajc

#define TWO(X) (1LL<<(X))
#define CONTAIN(S,X) ((S) & TWO(X))

int rand16() {
    return rand() & (TWO(16) - 1);
}
int my_rand() {
    return rand16() << 32 | rand16() << 16 | rand16();
}

double safe_sqrt(double x) { return sqrt(max((double)0.0, x)); }
int GI(int& x) { return scanf("%lld", &x); }

template<class Flow=int, class Cost=int>
struct MinCostFlow {
    const Flow INF_FLOW = 1000111000;
    const Cost INF_COST = 1000111000111000LL;

    int n, t, S, T;
    Flow totalFlow;
    Cost totalCost;
    vector<int> last, visited;
    vector<Cost> dis;
    struct Edge {
        int to;
        Flow cap;
        Cost cost;
        int next;
        Edge(int to, Flow cap, Cost cost, int next) :
                to(to), cap(cap), cost(cost), next(next) {}
    };
    vector<Edge> edges;

    MinCostFlow(int n) : n(n), t(0), totalFlow(0), totalCost(0), last(n, -1), visited(n, 0), dis(n, 0) {
        edges.clear();
    }

    int addEdge(int from, int to, Flow cap, Cost cost) {
        edges.push_back(Edge(to, cap, cost, last[from]));
        last[from] = t++;
        edges.push_back(Edge(from, 0, -cost, last[to]));
        last[to] = t++;
        return t - 2;
    }

    pair<Flow, Cost> minCostFlow(int _S, int _T) {
        S = _S; T = _T;
        SPFA();
        while (1) {
            while (1) {
                REP(i,n) visited[i] = 0;
                if (!findFlow(S, INF_FLOW)) break;
            }
            if (!modifyLabel()) break;
        }
        return make_pair(totalFlow, totalCost);
    }

private:
    void SPFA() {
        REP(i,n) dis[i] = INF_COST;
        priority_queue< pair<Cost,int> > Q;
        Q.push(make_pair(dis[S]=0, S));
        while (!Q.empty()) {
            int x = Q.top().second;
            Cost d = -Q.top().first;
            Q.pop();
            // For double: dis[x] > d + EPS
            if (dis[x] != d) continue;
            for(int it = last[x]; it >= 0; it = edges[it].next)
                if (edges[it].cap > 0 && dis[edges[it].to] > d + edges[it].cost)
                    Q.push(make_pair(-(dis[edges[it].to] = d + edges[it].cost), edges[it].to));
        }
        Cost disT = dis[T]; REP(i,n) dis[i] = disT - dis[i];
    }

    Flow findFlow(int x, Flow flow) {
        if (x == T) {
            totalCost += dis[S] * flow;
            totalFlow += flow;
            return flow;
        }
        visited[x] = 1;
        Flow now = flow;
        for(int it = last[x]; it >= 0; it = edges[it].next)
            // For double: fabs(dis[edges[it].to] + edges[it].cost - dis[x]) < EPS
            if (edges[it].cap && !visited[edges[it].to] && dis[edges[it].to] + edges[it].cost == dis[x]) {
                Flow tmp = findFlow(edges[it].to, min(now, edges[it].cap));
                edges[it].cap -= tmp;
                edges[it ^ 1].cap += tmp;
                now -= tmp;
                if (!now) break;
            }
        return flow - now;
    }

    bool modifyLabel() {
        Cost d = INF_COST;
        REP(i,n) if (visited[i])
            for(int it = last[i]; it >= 0; it = edges[it].next)
                if (edges[it].cap && !visited[edges[it].to])
                    d = min(d, dis[edges[it].to] + edges[it].cost - dis[i]);

        // For double: if (d > INF_COST / 10)     INF_COST = 1e20
        if (d == INF_COST) return false;
        REP(i,n) if (visited[i])
            dis[i] += d;
        return true;
    }
};


int32_t main() {
    freopen("fmcm.in", "r", stdin);
    freopen("fmcm.out", "w", stdout);

    ios::sync_with_stdio(0);
    cin.tie(0);
    cout << (fixed) << setprecision(9) << boolalpha;
    int n, m, s, t;
    while (cin >> n >> m >> s >> t) {
        --s; --t;
        MinCostFlow<int,int> flow(n);
        FOR(i,1,m) {
            int u, v, fl, c; cin >> u >> v >> fl >> c;
            --u;
            --v;
            flow.addEdge(u, v, fl, c);
        }
        auto res = flow.minCostFlow(s, t);
        cout << res.second << endl;
    }
}