#include <bits/stdc++.h>
using namespace std;
const int NMAX  = 355;
struct edge
{
    int from , to , flow , cost;
};
int n , s ,t;
vector <int> adia[NMAX];
int cap[NMAX][NMAX] , p[NMAX] , d[NMAX] , cost[NMAX][NMAX],viz[NMAX];
bool bellman()
{
    int i;
    for(i = 1 ; i <= n; ++i)d[i]=1e9;
    for(i=1;i<=n;++i)p[i]=-1;
    memset(viz,0,sizeof(viz));
    queue <int> q;
    q.push(s);
    d[s] = 0;
    viz[s] = 1;
    while(!q.empty())
    {
        int nod = q.front();
        q.pop();
        viz[nod] =0 ;
        for(int i : adia[nod])
        {
            if(cap[nod][i] <= 0)continue;
            if(d[i] > d[nod] + cost[nod][i])
            {
                d[i] = d[nod] + cost[nod][i];
                if(!viz[i])
                {
                    q.push(i);
                    viz[i]=1;
                }
                p[i] = nod;
            }
        }
    }
    return d[t]!=1e9;
}
int get_flow()
{
    int t1 = t;
    int f = 1e9;
    for(;t1!=s;t1=p[t1])
        f = min(f,cap[p[t1]][t1]);
    return f;
}
int opt_flow(int flux)
{
    int t1 = t;
    for(;t1!=s;t1=p[t1])
    {
        cap[p[t1]][t1]-=flux;
        cap[t1][p[t1]]+=flux;
    }
    return flux* d[t];
}
int min_cost_flow()
{
    int cost = 0 ;
    while(bellman())
        cost += opt_flow(get_flow());
    return cost;
}
int main()
{
    freopen("fmcm.in","r",stdin);
    freopen("fmcm.out","w",stdout);
    int m,s1,d1;
    cin>>n>>m>>s>>t;
    for(int i=1;i<=m;i++)
    {
        int a,b,c,d;
        cin>>a>>b>>c>>d;
        cap[a][b] = c;
        cap[b][a] = 0;
        cost[a][b] = d;
        cost[b][a] = -d;
        adia[a].push_back(b);
        adia[b].push_back(a);
    }
    int res=min_cost_flow();
    cout<<res;
    return 0;
}