/*
    Look at me!
    Look at me!
    The monster inside me has grown this big!
*/
 
#include<fstream>
#include<iostream>
#include<cstdio>
#include<map>
#include<set>
#define FIT(a,b) for(vector<int >::iterator a=b.begin();a!=b.end();a++)
#define RIT(a,b) for(vector<int>::reverse_iterator a=b.end();a!=b.begin();++a)
#include<stack>
#define ROF(a,b,c) for(int a=b;a>=c;--a)
#include<vector>
#include<algorithm>
#define FOR(a,b,c) for(int a=b;a<=c;++a)
#define REP(a,b) for(register int a=0;a<b;++a)
#include<cstring>
#include<bitset>
#include<cmath>
#include<iomanip>
#include<queue>
#define debug cerr<<"OK";
#define pii pair<int,int>
#define mp make_pair
#define pb push_back
#define fi first
#define se second
#define ll long long
#define ull unsigned long long
#define eps 1.e-10
#define N 360
#define mod 1999999973
#define inf 0x3f3f3f3f
using namespace std;
/*int dx[]={0,0,0,1,-1};
int dy[]={0,1,-1,0,0};*/
ifstream f("fmcm.in");
ofstream g("fmcm.out");
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));
	memset(fd,0x3f,sizeof(fd));
	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;
		FIT(it,v[x])
		if(C[x][*it]!=F[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;
			}
		}
	}
	memcpy(old,D,sizeof(D));
	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]-F[T[x]][x]);
	cost+=flux*D[d];
	for(int x=d;x!=s;x=T[x])
	{
		F[T[x]][x]+=flux;
		F[x][T[x]]-=flux;
	}
	return 1;
}
void Blat(int x)
{
	memset(old,0x3f,sizeof(old));
	q.push(x);
	viz[x]=1;
	old[x]=0;
	while(!q.empty())
	{
		x=q.front();
		q.pop();
		viz[x]=0;
		FIT(it,v[x])
		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 ()
{
	f>>n>>m>>s>>d;
	FOR(i,1,m)
	{
		f>>x>>y;
		f>>C[x][y]>>Z[x][y];
		Z[y][x]=-Z[x][y];
		v[x].pb(y);
		v[y].pb(x);
	}
	Blat(s);
	while(Dijman());
	g<<cost;
	return 0;
}