#include<bits/stdc++.h>
#define M 25010
#define N 351
using namespace std;
ifstream f("fmcm.in");
ofstream g("fmcm.out");
int n,m,s,d,i,j,k,cp,cs,cap[N][N],flow[N][N],q[N],dad[N],P[N],price[N][N],PRICE,djikstra(),LH,H[N],PH[N],oo=2000000000;
vector<int> v[N];
void upd(),bellman();
int main()
{
    f>>n>>m>>s>>d;
    for(;m;m--)
    {
        int i,j,cp,cs;
        f>>i>>j>>cp>>cs;
        cap[i][j]=cp;
        price[i][j]=cs;
        price[j][i]=-cs;
        v[i].push_back(j);
        v[j].push_back(i);
    }
    bellman();
    for(;djikstra();)
        upd();
    g<<PRICE;
    return 0;
}
void bellman()
{
    for(i=1;i<=n;i++)
        P[i]=oo;
    P[s]=0;
    dad[s]=s;
    dad[d]=0;
    queue<int> Q;
    Q.push(s);
    q[s]=1;
    for(;Q.size();)
    {
        int nod=Q.front();
        Q.pop();q[m]=0;
        for(auto vec:v[nod])
            if(cap[nod][vec]-flow[nod][vec]>0&&P[vec]>P[nod]+price[nod][vec])
            {
                if(!q[vec])
                {
                    q[vec]=1;
                    Q.push(vec);
                }
                dad[vec]=nod;
                P[vec]=P[nod]+price[nod][vec];
            }

    }
    cs=P[d];
}
int djikstra()
{
    for(i=1;i<=n;i++)
    {
        if(P[i]==oo)continue;
        for(auto vec:v[i])
        {
            if(P[vec]==oo)continue;
            price[i][vec]+=P[i]-P[vec];
        }
    }
    for(i=1;i<=n;i++)
    {
        P[i]=oo;
        dad[i]=i;
    }
    priority_queue<pair<int,int>> pq;
    pq.push(make_pair(0,s));
    P[s]=0;
    while(pq.size())
    {
        int nod,cst;
        tie(cst,nod)=pq.top();
        pq.pop();
        cst=-cst;
        for(auto vec:v[nod])
            if(flow[nod][vec]<cap[nod][vec])
                if(P[vec]>P[nod]+price[nod][vec])
                {
                    P[vec]=P[nod]+price[nod][vec];
                    pq.push(make_pair(-P[vec],vec));
                    dad[vec]=nod;
                }
    }
    return P[d]==oo?0:1;
}
void upd()
{
    cs+=P[d];
    for(m=oo,i=d,j=dad[d];i-j;i=dad[i],j=dad[j])
        m=min(m,cap[j][i]-flow[j][i]);
    PRICE+=m*cs;
    for(i=d,j=dad[d];i-j;i=dad[i],j=dad[j])
        {
            flow[i][j]-=m;
            flow[j][i]+=m;
        }
}