#include <fstream>
#include <cassert>
#include <cstring>
#include <queue>
#include <vector>
#define INFI 0x3f3f3f3f
using namespace std;
#define MAXN 355
ifstream f("fmcm.in");
ofstream g("fmcm.out");
int N, M, S, D;
int C[MAXN][MAXN], Cost[MAXN][MAXN];
vector<int> con[MAXN];
int F, FCost;
int old_d[MAXN]; char inQ[MAXN];
queue<int> Q;
int d[MAXN], real_d[MAXN], p[MAXN];
priority_queue<pair<int, int>, vector<pair<int, int> >, greater<pair<int, int> > > H;

inline bool dijkstra()
{
    memset(d, 0x3f, sizeof(d));
    d[S] = 0; real_d[S] = 0;
    H.push(make_pair(d[S], S));

    for (; !H.empty(); )
    {
        int cost = H.top().first, nod = H.top().second;
        H.pop();
        if (d[nod] != cost)
            continue;

        vector<int> :: iterator it;
        for (it = con[nod].begin(); it != con[nod].end(); it++)
            if (C[nod][*it])
            {
                int new_d = d[nod] + Cost[nod][*it] + old_d[nod] - old_d[*it];
                if (new_d < d[*it])
                {
                    d[*it] = new_d;
                    real_d[*it] = real_d[nod] + Cost[nod][*it];
                    p[*it] = nod;
                    H.push(make_pair(d[*it], *it));
                }
            }
    }
    memcpy(old_d, real_d, sizeof(d));
    if (d[D] == INFI)
        return false;

    int Min = INFI, curCost = 0;
    for (int aux = D; aux != S; aux = p[aux])
        Min = min(Min, C[p[aux]][aux]),
        curCost += Cost[p[aux]][aux];

    F += Min;
    FCost += Min * real_d[D];
    for (int aux = D; aux != S; aux = p[aux])
        C[p[aux]][aux] -= Min,
        C[aux][p[aux]] += Min;

    return true;
}

inline void bellmanFord()
{
    memset(old_d, 0x3f, sizeof(old_d));
    old_d[S] = 0;

    for (Q.push(S), inQ[S] = 1; !Q.empty(); Q.pop())
    {
        vector<int> :: iterator it;
        int i = Q.front();
        inQ[i] = 0;

        for (it = con[i].begin(); it != con[i].end(); it++)
            if (C[i][*it])
            {
                if (old_d[i] + Cost[i][*it] >= old_d[*it])
                    continue;

                old_d[*it] = old_d[i] + Cost[i][*it];

                if (inQ[*it]) continue;

                inQ[*it] = 1;
                Q.push(*it);
            }
    }

}

int main()
{
    f>>N>>M>>S>>D;

    for (; M; M--)
    {
        int x, y;
        f>>x>>y;
        f>>C[x][y]>>Cost[x][y];
        con[x].push_back(y);
        con[y].push_back(x);
        Cost[y][x] = -Cost[x][y];
    }
    F=FCost=0;
    bellmanFord();
    for (; dijkstra(); );
    g<<FCost;
    return 0;
}