#include <iostream>
#include <fstream>
#include <queue>
#include <vector>
using namespace std;
ifstream f ("fmcm.in");
ofstream g ("fmcm.out");
struct elem{
int nod,cost;
bool operator < (const elem &aux)
const{
        return aux.cost<cost;
    }
};
int dist[351],distdj1[351],distdj2[351],capacitate[351][351],costuri[351][351];
bool viz[351];
vector<pair<int,int>>muchii;
priority_queue < elem>q;
vector<int>adiacenta[351];
int n,m,s,d,rasp_cost;
int tati[351];
void bellman()
{
    for(int i = 1;i<=n;i++)
        dist[i]=(1<<30)-1;
    dist[s] = 0;
    q.push({s,0});

    while(!q.empty())
    {
        int curent = q.top().nod;
        int cost_curent = q.top().cost;
        q.pop();
        for(auto x:adiacenta[curent])
        {
            int nod_nou = x;
            int cost_nou = costuri[curent][nod_nou];

            if(dist[nod_nou]>cost_curent+cost_nou && capacitate[curent][nod_nou])
            {
                dist[nod_nou]= cost_curent+cost_nou;
                q.push({nod_nou,dist[nod_nou]});
            }
        }

    }
}
bool dj()
{
    for(int i = 1;i<=n;i++)
    {
        distdj1[i] = distdj2[i] = (1<<30)-1;
        tati[i] = i;
        viz[i] = 0;
    }
    q.push({s,0});
    distdj1[s] = distdj2[s] = 0;
    while(!q.empty())
    {
        int curent = q.top().nod;
        int cost = q.top().cost;
        q.pop();
        if(distdj1[curent]!=cost)
            continue;
        for(auto x:adiacenta[curent])
        {
            if(capacitate[curent][x]!=0)
            {
                int nouadist = distdj1[curent]+costuri[curent][x]+dist[curent]-dist[x];
                if(nouadist <distdj1[x])
                {
                    distdj1[x] = nouadist;
                    q.push({x,distdj1[x]});
                    distdj2[x] = distdj2[curent]+costuri[curent][x];
                    tati[x] = curent;

                }
            }
        }

    }
    if(distdj1[d]!=(1<<30)-1)
        return 1;

    return 0;
}
int main()
{
    std::ios::sync_with_stdio(false);
    f >> n >> m>>s>>d;
    for(int i=1;i<=m;i++)
    {
        int x,y,c,cost;
        f >> x >> y >> c>>cost;
        muchii.push_back({x,y});
        adiacenta[x].push_back(y);
        adiacenta[y].push_back(x);
        capacitate[x][y]=c;
        costuri[x][y] = cost;
        costuri[y][x] = -cost;
    }
    bellman();
    while(dj())
    {
                int flux = (1<<30)-1;
                int nod_start = d;

                while(nod_start!=s)
                {
                    flux = min(flux,capacitate[tati[nod_start]][nod_start]);
                    nod_start = tati[nod_start];
                }
                nod_start = d;
                if(flux==0)
                    continue;

                while(nod_start!=s)
                {
                    capacitate[tati[nod_start]][nod_start] -=flux;
                    capacitate[nod_start][tati[nod_start]] +=flux;
                    nod_start=tati[nod_start];
                }
                rasp_cost+=flux*distdj2[d];

    }
    g << rasp_cost;
}