#include<cstdio>
#include<deque>
#include<cstring>
#include<queue>
#include<algorithm>
#include<vector>
const int nmax=350;
const int mmax=12500;
const int inf=2000000000;
using namespace std;
int n,m,s,t;
int flux[nmax+5][nmax+5];
int ca[nmax+5][nmax+5],co[nmax+5][nmax+5],ta[nmax+5],cv[nmax+5];
deque<int> que;
bool be[nmax+5],inq[nmax+5];
vector<int > ve[nmax+5];
priority_queue<pair<int,int> ,vector<pair<int,int> >,greater<pair<int, int> > > pq;
void belman()
{
    int x,i;
     memset(cv,inf,sizeof(cv));
    cv[s]=0;
    que.push_back(s);
    inq[s]=1;
    while(!que.empty())
    {
        x=que.back();
        que.pop_back();
        for(i=ve[x].size()-1; i>=0; i--)
            if(ca[x][ve[x][i]]>0 && cv[x]+co[x][ve[x][i]]<cv[ve[x][i]])
            {
                cv[ve[x][i]]=cv[x]+co[x][ve[x][i]];
                if(inq[ve[x][i]]==0)
                {
                    inq[ve[x][i]]=1;
                    que.push_back(ve[x][i]);
                }
            }
        inq[x]=0;
    }

}
int oldd[nmax+5],newd[nmax+5],reald[nmax+5];
bool djkstra()
{
memset(newd, 0x3f, sizeof(newd));
    newd[s] = 0; reald[s] = 0;
    pq.push(make_pair(newd[s], s));

    for (; !pq.empty(); )
    {
        int cst = pq.top().first, nod = pq.top().second;
        pq.pop();
        if (newd[nod] != cst)
            continue;

        vector<int> :: iterator it;
        for (it = ve[nod].begin(); it != ve[nod].end(); it++)
            if (ca[nod][*it]-flux[nod][*it])
            {
                int new_d = newd[nod] + co[nod][*it] + oldd[nod] - oldd[*it];
                if (new_d < newd[*it])
                {
                    newd[*it] = new_d;
                    reald[*it] = reald[nod] + co[nod][*it];
                    ta[*it] = nod;
                    pq.push(make_pair(newd[*it], *it));
                }
            }
    }
    memcpy(oldd, reald, sizeof(newd));
    if (newd[t] == 0x3f3f3f3f)
        return 0;
    else
    return 1;
}
void da()
{
    int i,cmin,z;
    belman();
    for(i=1;i<=n;i++)
    oldd[i]=cv[i];
    while(djkstra())
    {
        cmin=-1;
        z=t;
        while(z!=s)
        {
            if(ca[ta[z]][z]-flux[ta[z]][z]<cmin || cmin==-1)
                cmin=ca[ta[z]][z]-flux[ta[z]][z];
            z=ta[z];
        }
        z=t;
        while(z!=s)
        {
            flux[ta[z]][z]+=cmin;
            flux[z][ta[z]]-=cmin;
            z=ta[z];
        }
    }
}
int main()
{
    freopen("fmcm.in","r",stdin);
    freopen("fmcm.out","w",stdout);
    int i,j,x,y,cmin;
    scanf("%d%d%d%d",&n,&m,&s,&t);
    for(i=1; i<=m; i++)
    {
        scanf("%d%d",&x,&y);
        scanf("%d%d",&ca[x][y],&co[x][y]);
        co[y][x]=-co[x][y];
        ve[x].push_back(y);
        ve[y].push_back(x);
    }
    da();
    cmin=0;
    for(i=1; i<=n; i++)
        for(j=1; j<=n; j++)
            if(flux[i][j]>0)
            {
                cmin=cmin+flux[i][j]*co[i][j];
            }
    printf("%d\n",cmin);
    return 0;
}