#include <algorithm>
#include <vector>
using namespace std;

#define DIM 355
#define pb push_back
#define oo 1<<31-1

vector <int> lst[DIM];
int c[DIM][DIM],f[DIM][DIM],ct[DIM][DIM];
int q[DIM*DIM],viz[DIM],t[DIM],dist[DIM],h[DIM],poz[DIM],lim[DIM];
int n,m,s,d,minim,sum,l;
long long cost;

void read ()
{
    int i,x,y,z,t;

    scanf ("%d%d%d%d",&n,&m,&s,&d);
    for (i=1; i<=m; ++i)
    {
        scanf ("%d%d%d%d",&x,&y,&z,&t);
        lst[x].pb (y);
        lst[y].pb (x);
        c[x][y]=z;
        ct[x][y]=t;
        ct[y][x]=-t;
    }
}

inline void init ()
{
    int i;

    for (i=1; i<=n; ++i)
    {
        t[i]=viz[i]=0;
        dist[i]=oo;
        h[i]=poz[i]=i;
    }
}

void bellman_ford ()
{
    int i,st,dr;

    for (i=1; i<=n; ++i)
        lim[i]=(int)lst[i].size ();
    init ();
    for (dist[q[st=dr=1]=s]=0; st<=dr; viz[q[st++]]=0)
        for (i=0; i<lim[st]; ++i)
            if (c[q[st]][lst[st][i]]>f[q[st]][lst[st][i]] && dist[q[st]]+ct[q[st]][lst[st][i]]<dist[lst[st][i]])
            {
                dist[lst[st][i]]=dist[q[st]]+ct[q[st]][lst[st][i]];
                t[lst[st][i]]=q[st];
                if (!viz[lst[st][i]])
                    viz[q[++dr]=lst[st][i]]=1;
            }
    sum=dist[d];
}

inline void swap (int &a,int &b)
{
    int aux=a;

    a=b;
    b=aux;
}

inline void upheap (int x)
{
	for ( ; x/2>1 && dist[h[x]]<dist[h[x/2]]; x/=2)
	{
	    swap (h[x],h[x/2]);
		poz[h[x]]=x;
		poz[h[x/2]]=x/2;
	}
}

inline void downheap (int x)
{
	int y;

	for (y=0; x!=y; )
	{
		y=x;
		if (y*2<=l && dist[h[x]]>dist[h[y*2]])
            x=y*2;
		if (y*2+1<=l && dist[h[x]]>dist[h[y*2+1]])
            x=y*2+1;
		swap (h[x],h[y]);
		poz[h[x]]=x;
		poz[h[y]]=y;
	}
}

int dijkstra ()
{
    int i,j;

    for (i=1; i<=n; ++i)
		for (j=0; j<lim[i]; ++j)
			if (dist[i]!=oo && dist[lst[i][j]]!=oo)
                ct[i][lst[i][j]]+=dist[i]-dist[lst[i][j]];
    init ();
    for (dist[h[poz[s]=1]=s]=0, h[poz[1]=s]=1, l=n; l>1 && dist[h[1]]!=oo; )
    {
        for (i=0; i<lim[h[1]]; ++i)
            if (c[h[1]][lst[h[1]][i]]>f[h[1]][lst[h[1]][i]] && dist[h[1]]+ct[h[1]][lst[h[1]][i]]<dist[lst[h[1]][i]])
            {
				dist[lst[h[1]][i]]=dist[h[1]]+ct[h[1]][lst[h[1]][i]];
				t[lst[h[1]][i]]=h[1];
				upheap (poz[lst[h[1]][i]]);
			}

        poz[h[1]=h[l--]]=1;
        if (l>1)
            downheap (1);
    }


    if (dist[d]!=oo)
        return 1;
    return 0;
}

inline int min (int a,int b)
{
    if (a<b)
        return a;
    return b;
}

void solve ()
{
    int i;

    for (minim=oo; dijkstra (); minim=oo)
    {
        for (i=d; i!=s; i=t[i])
            minim=min (minim,c[t[i]][i]-f[t[i]][i]);
        for (i=d; i!=s; i=t[i])
        {
            f[t[i]][i]+=minim;
            f[i][t[i]]-=minim;
        }
        sum+=dist[d];
        cost+=minim*sum;
    }
    printf ("%lld",cost);
}

int main ()
{
    freopen ("fmcm.in","r",stdin);
    freopen ("fmcm.out","w",stdout);

    read ();
    bellman_ford ();
    solve ();

    return 0;
}