#include<iostream.h>
#include<fstream.h>
#define u (1<<30)
int ver[25999],leg[25999],cost[25999],c[359][359],d[359],h[359],hh[359],n,L,S,D,start[359],sum,rez,fa[359];
void bf()
{
	int i,ok=1,t;
	for(i=1;i<=n;i++)
		d[i]=u;
	d[S]=0;
	while(ok)
	{
		ok=0;
		for(i=1;i<=n;i++)
		{
			t=start[i];
			while(t)
			{
				if(c[i][ver[t]]&&d[ver[t]]>d[i]+cost[t])
				{
					d[ver[t]]=d[i]+cost[t];
					ok=1;
				}
				t=leg[t];
			}
		}
	}
	sum=d[D];
}	
void percolate(int nod)
{
	int safe=h[nod];
	while(nod>1&&d[h[nod>>1]]>d[safe])
	{
		hh[h[nod>>1]]=nod;
		h[nod]=h[nod>>1];
		nod>>=1;
	}
	hh[safe]=nod;
	h[nod]=safe;
}
int root()
{
	int safe=h[1],son,ls,rs,nod=1;
	hh[h[L]]=1;
	h[1]=h[L--];
	do
	{
		son=0;
		ls=(nod<<1);
		rs=1+ls;
		if(ls<=L)
		{
			son=ls;
			if(rs<=L&&d[h[rs]]<d[h[ls]])
				son=rs;
			if(d[h[son]]>=d[h[nod]])
				son=0;
		}
		if(son)
		{
			hh[h[son]]=nod;
			hh[h[nod]]=son;
			ls=h[nod];
			h[nod]=h[son];
			h[son]=ls;
			nod=son;
		}
	}
	while(son);
	hh[safe]=0;
	return safe;
}
int dijkstra()
{
	int i,t,min=u,nod;
	for(i=1;i<=n;i++)
	{
		t=start[i];
		while(t)
		{
			if(d[i]!=u&&d[ver[t]]!=u)
				cost[t]+=d[i]-d[ver[t]];
			t=leg[t];
		}
	}
	for(i=1;i<=n;i++)
	{
		d[i]=u;
		h[i]=hh[i]=i;
		fa[i]=0;
	}
	d[S]=0;
	hh[S]=h[S]=1;
	hh[1]=h[1]=S;
	L=n;
	while(L)
	{
		nod=root();
		t=start[nod];
		while(t)
		{
			if(hh[ver[t]]&&c[nod][ver[t]]&&d[ver[t]]>d[nod]+cost[t])
			{
				d[ver[t]]=d[nod]+cost[t];
				fa[ver[t]]=nod;
				percolate(hh[ver[t]]);
			}
			t=leg[t];
		}
	}
	if(d[D]!=u)
	{
		i=D;
		while(i!=S)
		{
			if(min>c[fa[i]][i])
				min=c[fa[i]][i];
			i=fa[i];
		}
		i=D;
		while(i!=S)
		{
			c[fa[i]][i]-=min;
			c[i][fa[i]]+=min;
			i=fa[i];
		}
		sum+=d[D];
		rez+=min*sum;
		return 1;
	}
	return 0;
}	
int main()
{
	int m,x,y,cap,z,q=0;
	ifstream fin("fmcm.in");
	ofstream g("fmcm.out");
	fin>>n>>m>>S>>D;
	while(m--)
	{
		fin>>x>>y>>cap>>z;
		ver[++q]=y;
		leg[q]=start[x];
		start[x]=q;
		c[x][y]=cap;
		cost[q]=z;
		ver[++q]=x;
		leg[q]=start[y];
		start[y]=q;
		cost[q]=-z;
	}
	bf();
	while(dijkstra());
	g<<rez;
	return 0;
}