/*
    Look at me!
    Look at me!
    The monster inside me has grown this big!
*/

#include<cstdio>
#include<stack>
#include<vector>
#include<algorithm>
#include<cstring>
#include<queue>
#define pii pair<int,int>
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define inf 1<<30
#define N 360
using namespace std;
/*int dx[]={0,0,0,1,-1};
int dy[]={0,1,-1,0,0};*/

vector<int> v[N];
queue<int> q;
priority_queue<pii > pq;
int D[N],fd[N],T[N],old[N],F[N][N],viz[N],n,d,s,cost,m,x,y,Z[N][N],C[N][N];
bool Dijman()
{
    memset(viz,0,sizeof(viz));
    for(int i=1;i<=n;++i)
        fd[i]=D[i]=inf;
    fd[s]=D[s]=0;
    pq.push(mp(0,s));
    while(!pq.empty())
    {
        while(!pq.empty()&&viz[pq.top().se])
            pq.pop();
        if(pq.empty())
            break;
        int x=pq.top().se;
        pq.pop();
        viz[x]=1;
        for(vector<int>::iterator it=v[x].begin();it!=v[x].end();++it)
        if(C[x][*it])
        {
            int costu=fd[x]+Z[x][*it]+old[x]-old[*it];
            if(costu<fd[*it])
            {
                fd[*it]=costu;
                pq.push(mp(-fd[*it],*it));
                D[*it]=D[x]+Z[x][*it];
                T[*it]=x;
            }
        }
    }
    // for(int i=1;i<=n;++i)
    // old[i]=D[i];
    if(D[d]==inf)
        return 0;
    int flux=n;
    for(int x=d;x!=s;x=T[x])
        flux=min(flux,C[T[x]][x]);
    cost+=flux*D[d];
    for(int x=d;x!=s;x=T[x])
    {
        C[T[x]][x]-=flux;
        C[x][T[x]]+=flux;
    }
    return 1;
}
void Blat(int x)
{
    for(int i=1;i<=n;++i)
        old[i]=inf;
    q.push(x);
    viz[x]=1;
    old[x]=0;
    while(!q.empty())
    {
        x=q.front();
        q.pop();
        viz[x]=0;
        for(vector<int>::iterator it=v[x].begin();it!=v[x].end();++it)
        if(C[x][*it])
        {
            if(old[x]+Z[x][*it]>=old[*it])
                continue;
            old[*it]=old[x]+Z[x][*it];
            if(viz[*it])
                continue;
            viz[*it]=1;
            q.push(*it);
        }
    }
}
int main ()
{
    freopen("fmcm.in","r",stdin);
    freopen("fmcm.out","w",stdout);

    scanf("%d%d%d%d",&n,&m,&s,&d);
    for(int i=1;i<=m;++i)
    {
        scanf("%d%d",&x,&y);
        scanf("%d%d",&C[x][y],&Z[x][y]);
        Z[y][x]=-Z[x][y];
        v[x].pb(y);
        v[y].pb(x);
    }
    Blat(s);
    while(Dijman());
    printf("%d",cost);
    return 0;
}