#include<stdio.h>
#include<vector>
#include<set>
#include<queue>
#define inf 2000000000
using namespace std;
FILE*f=fopen("fmcm.in","r");
FILE*g=fopen("fmcm.out","w");
int x,y,z,T,n,m,k,d[351],nod,c[351][351],F[351][351],sol,minn,S,D,tt[351],s[351];
char viz[351];
vector <pair<int,int> > v[351];
set <pair<int,int> > t;
queue<int> q;
set<pair<int,int> >::iterator it;
int dijkstra()
{
	int min=inf;
	int k;
	if(!t.empty())
	{
		it=t.begin();
		min=it->first;
		k=it->second;
		d[k]=min;
		while(!t.empty()&&viz[it->second])
		{
			t.erase (it);
			if(!t.empty())
				it=t.begin();
		}
	}
	if(min!=inf)
	{
		viz[k]=1;
		for(int i=0;i<v[k].size();++i)
			if(!viz[v[k][i].first])
				if(d[v[k][i].first]>d[k]+v[k][i].second&&c[k][v[k][i].first]>F[k][v[k][i].first])
				{
					d[v[k][i].first]=d[k]+v[k][i].second;
					tt[v[k][i].first]=k;
					t.insert (make_pair(d[v[k][i].first],v[k][i].first));
				}
		dijkstra();
	}
	if(d[D]==inf)
		return 0;
	return 1;
}
void update()
{
	for(int i=1;i<=n;++i)
		for(int j=0;j<v[i].size();++j)
			v[i][j].second+=d[i]-d[v[i][j].first];
	
}
int main()
{
	fscanf(f,"%d%d%d%d",&n,&m,&S,&D);
	for(int i=1;i<=m;++i)
	{
		fscanf(f,"%d%d%d%d",&x,&y,&z,&T);
		v[x].push_back (make_pair(y,T));
		v[y].push_back (make_pair(x,-T));
		c[x][y]=z;
	}
	
	for(int i=1;i<=n;++i)
		d[i]=inf;
	d[S]=0;
	q.push (S);
	viz[S]=1;
	k=1;
	
	while(k&&q.size())
	{
		nod=q.front();
		for(int i=0;i<v[nod].size();++i)
			if(d[v[nod][i].first]>d[nod]+v[nod][i].second&&c[nod][v[nod][i].first]-F[nod][v[nod][i].first]>0)
			{
				if(!viz[v[nod][i].first])
				{
					q.push (v[nod][i].first);
					tt[v[nod][i].first]=nod;
					viz[v[nod][i].first]=1;
				}
				d[v[nod][i].first]=d[nod]+v[nod][i].second;
				s[v[nod][i].first]++;
				if(s[v[nod][i].first]==n)
				{
					k=0;
					break;
				}
			}
		viz[nod]=0;
		q.pop();
	}
	update();
	int last=d[D];
	for(int i=1;i<=n;++i)
	{
		d[i]=inf;
		viz[i]=0;
	}
	d[S]=0;
	t.insert(make_pair(0,S));
	
	
	
	while(dijkstra())
	{
		minn=inf;
		for(int nod=D;nod!=S;nod=tt[nod])
			if(minn>c[tt[nod]][nod]-F[tt[nod]][nod])
				minn=c[tt[nod]][nod]-F[tt[nod]][nod];
		for(int nod=D;nod!=S;nod=tt[nod])
		{
			F[tt[nod]][nod]+=minn;
			F[nod][tt[nod]]-=minn;
		}
		
		sol+=d[D]*minn+last*minn;
		last+=d[D];
		update();
		for(int i=1;i<=n;++i)
		{
			d[i]=inf;
			viz[i]=0;
		}
		d[S]=0;
		t.insert(make_pair(0,S));
		
	}
	
	fprintf(g,"%d",sol);
	
	fclose(f);
	fclose(g);
	return 0;
}