#include <cstdio>
#include <vector>
#include <queue>
#include <cstring>
#include <algorithm>
using namespace std;
const int NMAX = 350;
const int INF = 2.e9;
vector <int> G[NMAX + 5];
int d[NMAX + 5] , cap[NMAX + 5][NMAX + 5] , cst[NMAX + 5][NMAX + 5] , p[NMAX + 5] , n;
struct path
{
    int nod , cost;
    path(int x = 0 , int y = 0)
    {
        nod = x;
        cost = y;
    }
};
bool operator<(const path& a , const path& b)
{
    return a.cost > b.cost;
}
int dijkstra(int s , int t)
{
    int i , u , v , cost , new_cost;
    for(i = 1 ; i <= n ; i ++)
        d[i] = INF;
    d[s] = 0;
    priority_queue <path> pq;
    pq.push(path(s , 0));
    while(!pq.empty())
    {
        u = pq.top().nod;
        cost = pq.top().cost;
        pq.pop();
        if(d[u] < cost)
            continue;
        for(i = 0 ; i < G[u].size() ; i ++)
        {
            v = G[u][i];
            if(cap[u][v])
            {
                new_cost = d[u] + cst[u][v];
                if(new_cost < d[v])
                {
                    d[v] = new_cost;
                    p[v] = u;
                    pq.push(path(v , new_cost));
                }
            }
        }
    }
    if(d[t] == INF)
        return 0;
    return 1;
}
inline int get_flow(int s , int t)
{
    int flow , nod;
    flow = INF;
    for(nod = t ; nod != s ; nod = p[nod])
        flow = min(flow , cap[p[nod]][nod]);
    return flow;
}
inline int set_flow(int s , int t , int flow)
{
    for(int nod = t ; nod != s ; nod = p[nod])
    {
        cap[p[nod]][nod] = cap[p[nod]][nod] - flow;
        cap[nod][p[nod]] = cap[nod][p[nod]] + flow;
    }
    return flow * d[t];
}
int fmcm(int s , int t)
{
    int cost = 0;
    while(dijkstra(s , t))
        cost += set_flow(s , t , get_flow(s , t));
    return cost;
}
int main()
{
    freopen("fmcm.in" , "r" , stdin);
    freopen("fmcm.out" , "w" , stdout);
    int m , s , t , i , j , x , y , c , z;
    scanf("%d%d%d%d" , &n , &m , &s , &t);
    for(i = 1 ; i <= m ; i ++)
    {
        scanf("%d%d%d%d" , &x , &y , &c , &z);
        G[x].push_back(y);
        G[y].push_back(x);
        cap[x][y] = c;
        cst[x][y] = z;
        cst[y][x] = -z;
    }
    printf("%d\n" , fmcm(s , t));
    return 0;
}