#include <bits/stdc++.h>
using namespace std;
const int NMAX  = 100005;
struct Dinic
{
    struct edge
    {
        int from , to , flow , cost;
    };
    vector< edge> edges;
    vector< int> dist , adia[NMAX], tata;
    int n , s, d, sum = 0;
    void addedge(int fr , int to , int flux , int p)
    {
        edges.push_back({fr,to,flux,p});
        adia[fr].push_back(edges.size()-1);
        edges.push_back({to,fr,0,-p});
        adia[to].push_back(edges.size()-1);

    }
    bool bellman()
    {
        queue<int>q;
        q.push(s);
        fill(dist.begin(),dist.end(),1e9);
        fill(tata.begin(),tata.end(),-1);
        vector<int>viz(n+1,0);
        dist[s] = 0 ;
        viz[s] =1 ;
        tata[s]=0;
        while(!q.empty())
        {
            int nod = q.front();
            q.pop();
            viz[nod] = 0;
            for(int i :adia[nod])
            {
                edge e = edges[i];
                if(!e.flow)continue;
                if(tata[e.to]==-1)
                {
                    dist[e.to] = dist[nod] + e.cost;
                    tata[e.to] = i;
                    viz[e.to] = 1;
                    q.push(e.to);
                }
                else
                {
                    if(dist[e.to] > dist[nod] + e.cost && tata[nod]!=(i^1))
                    {
                        dist[e.to] = dist[nod] + e.cost;
                        if(!viz[e.to])q.push(e.to);
                        viz[e.to] = 1;
                        tata[e.to] = i;
                    }
                }
            }
        }
        return (dist[d]!=1e9);
    }
    int dfs(int nod , int flux)
    {
        if(nod == s)
            return flux;
        else
        {
          edge &e = edges[tata[nod]];
          int f = dfs(e.from , min(flux,e.flow));
          sum += f * e.cost;
          e.flow -= f;
          edges[tata[nod]^1].flow+=f;
          return f;
        }
    }
    int GetFlow()
    {
        int x = 0;
        while(bellman())
        {
            int flux = dfs(d , 1e9);
            x += flux;
        }
        return sum;
    }
    Dinic(int n1,int s1, int d1)
    {
        tata = dist = vector<int>(n+2,0);
        s = s1 ;
        n = n1;
        d = d1;
     }
};
int main()
{
    freopen("fmcm.in","r",stdin);
    freopen("fmcm.out","w",stdout);
    int n,m,s1,d1;
    cin>>n>>m>>s1>>d1;
    Dinic g(n,s1,d1);
    for(int i=1;i<=m;i++)
    {
        int a,b,c,d;
        cin>>a>>b>>c>>d;
        g.addedge(a,b,c,d);
    }
    int res=g.GetFlow();
    cout<<res;
    return 0;
}