#include <iostream>
#include <fstream>
#include <vector>
#include <queue>
#define nmax 355
using namespace std;
ifstream f("fmcm.in");
ofstream g("fmcm.out");
int n,m, viz[nmax], fx[nmax][nmax], cp[nmax][nmax], cost[nmax][nmax], t[nmax], d[nmax],dij[nmax],ans[nmax], sur,dest, C;
vector <int> v[nmax];
queue  <int> q;
priority_queue < pair< int, int > > qp;
void citire()
{
    int i,j,k,cap,cst;
    f>>n>>m>>sur>>dest;
    for(k=1; k<=m; k++)
    {
        f>>i>>j>>cap>>cst;
        v[i].push_back(j);
        v[j].push_back(i);
        cp[i][j]=cap;
        cost[i][j]=cst; cost[j][i]=-cst;
    }
}

void bellman_ford()
{
    int i,nod;
    for(i=1; i<=n; i++)
        d[i]=1e9;
    d[sur]=0;
    q.push(sur);
    while(!q.empty())
    {
        nod=q.front();
        q.pop();
        viz[nod]++;
        if(viz[nod]==n)
            return;
        for(i=0; i<v[nod].size(); i++)
            if( cp[nod][v[nod][i]]>fx[nod][v[nod][i]] && cost[nod][v[nod][i]]+d[nod]<d[v[nod][i]] )
        {
            d[v[nod][i]]=cost[nod][v[nod][i]]+d[nod];
            q.push(v[nod][i]);
        }
    }
}

int dijkstra()
{
    int nod,cst,i;
    for(i=1; i<=n; i++)
        {dij[i]=1e9; t[i]=0; viz[i]=0;}
    dij[sur]=0;
    qp.push({sur, 0});
    while(!qp.empty())
    {
        nod=qp.top().first;
        qp.pop();
        if(!viz[nod])
        {viz[nod]=1;
           for(i=0; i<v[nod].size(); i++)
              if( cp[nod][v[nod][i]]>fx[nod][v[nod][i]] && dij[nod]+cost[nod][v[nod][i]]  +d[nod]-d[v[nod][i]]  <dij[v[nod][i]] ) // dist x + costul > dist y
            {
                dij[v[nod][i]]=dij[nod]+cost[nod][v[nod][i]]+d[nod]-d[v[nod][i]];
                ans[v[nod][i]]=ans[nod]+cost[nod][v[nod][i]];
                t[v[nod][i]]=nod;
                qp.push({v[nod][i], -dij[v[nod][i]]});
            }

            for(i=1; i<=n; i++)
                d[i]=ans[i];

        }
    }
    return (dij[dest]!=1e9);
}

int flux()
{
    int nod, fmin;
    bellman_ford(); // apelez bellman pt a crea vectorul distantelor
    while(dijkstra())
    {
        fmin=1e9;
        for(nod=dest; nod!=sur; nod=t[nod])
            fmin=min(fmin, cp[t[nod]][nod]-fx[t[nod]][nod]);
        for(nod=dest; nod!=sur; nod=t[nod])
        {
            fx[t[nod]][nod]+= fmin;
            fx[nod][t[nod]]-= fmin;
        }
        C+= ans[dest]*fmin;
    }
    return C;
}

int main()
{
    citire();
    g<<flux();
    f.close();
    g.close();
    return 0;
}