#include<fstream>
#include<vector>
#include<queue>
#include<cstring>
#define vec G[nod][i]
#define NMAX 355
#define DIJKSTRA_TYPE pair<int,int> 
using namespace std;
int n,source,destination,FLUX[NMAX][NMAX],CAPACITY[NMAX][NMAX],COST[NMAX][NMAX];
int INF=(1<<30),VOLMIN,sol,TT[NMAX];
int old_DIST[NMAX],DIST[NMAX],real[NMAX];
vector<int> G[NMAX];
priority_queue<DIJKSTRA_TYPE, vector<DIJKSTRA_TYPE>, greater<DIJKSTRA_TYPE> > HEAP;
inline void init()
{
	for(int i=1;i<=n;i++)
		DIST[i]=INF;
}
void read()
{
	ifstream fin("fmcm.in");
	int m,z,c;
	fin>>n>>m>>source>>destination;
	int x,y;
	while(m--)
	{
		fin>>x>>y>>z>>c;
		G[x].push_back(y);
		G[y].push_back(x);
		CAPACITY[x][y]=z;
		COST[x][y]=c;
		COST[y][x]=-c;
	}
	fin.close();
}
void print()
{
	ofstream fout("fmcm.out");
	fout<<sol<<'\n';
	fout.close();
}
inline void flux_update()
{
	int i;
	VOLMIN=INF;
	for(i=destination;i!=source;i=TT[i])
		VOLMIN=min(VOLMIN,CAPACITY[TT[i]][i]);
	for(i=destination;i!=source;i=TT[i])
	{
		CAPACITY[TT[i]][i]-=VOLMIN;
		CAPACITY[i][TT[i]]+=VOLMIN;
	}
	sol+=(VOLMIN*real[destination]);
}
inline bool dijkstra()
{
	init();
	DIST[source]=0;
	real[source]=0;
	HEAP.push(make_pair(0,source));
	int nod,cst,cost;
	while(!HEAP.empty())
	{
		nod=HEAP.top().second;
		cst=HEAP.top().first;
		HEAP.pop();
		if(DIST[nod]!=cst)
			continue;
		for(size_t i=0;i<G[nod].size();i++)
			if(CAPACITY[nod][vec])
			{
				cost=COST[nod][vec]+old_DIST[nod]-old_DIST[vec];
				if(DIST[nod]+cost<DIST[vec])
				{
					DIST[vec]=DIST[nod]+cost;
					real[vec]=real[nod]+COST[nod][vec];
					TT[vec]=nod;
					HEAP.push(make_pair(DIST[vec],vec));
				}
			}
	}
	memcpy(old_DIST,real,sizeof DIST);
	return (DIST[destination]<INF);
}
int main()
{
	read();
	while(dijkstra())
		flux_update();
	print();
	return 0;
}