#include <iostream>
#include <fstream>
#include <vector>
#include <queue>

using namespace std;

ifstream f("fmcm.in");
ofstream g("fmcm.out");

#define cout g
#define nmax 355
#define inf 0x3f3f3f3f
#define foor(a,b) for(__typeof(b.begin()) a=b.begin();a!=b.end();++a)

int n,m,source,dest,cost_min,minn,nod;
int cap[nmax][nmax],cost[nmax][nmax],flux[nmax][nmax];
int from[nmax],dist[nmax];
vector <int> G[nmax];
bool in_queue[nmax];

void read();

bool bellman_ford()
{
    queue <int> q;
    int i,nod;
    for(i=1;i<=n;++i) dist[i]=inf,in_queue[i]=false;
    dist[source]=0;
    q.push(source);

    while (!q.empty())
    {
        nod=q.front();
        q.pop();
        in_queue[nod]=false;

        foor(it,G[nod])
        if(dist[*it]>dist[nod]+cost[nod][*it] && cap[nod][*it]-flux[nod][*it]!=0)
        {
            dist[*it]=dist[nod]+cost[nod][*it];
            from[*it]=nod;
            if(!in_queue[*it])
            {
                in_queue[*it]=true;
                q.push(*it);
            }
        }
    }

    if(dist[dest]==inf) return false;

    return true;


}

int main()
    {
    read();
    while(bellman_ford())
    {
        minn=inf;
        for(nod=dest;nod!=source;nod=from[nod]) minn=min(minn,cap[from[nod]][nod]-flux[from[nod]][nod]);
        for(nod=dest;nod!=source;nod=from[nod])
        {
            flux[from[nod]][nod]+=minn;
            flux[nod][from[nod]]-=minn;
        }
        cost_min+=minn*dist[dest];
    }
    cout<<cost_min;
    return 0;
    }

void read()
    {
    int i,a,b,c,z;
    f>>n>>m>>source>>dest;
    for(i=1; i<=m; ++i)
        {
        f>>a>>b>>c>>z;

        G[a].push_back(b);
        G[b].push_back(a);

        cost[a][b]=z;
        cap[a][b]=c;

        cost[b][a]=-z;
        }


    }