#include <bits/stdc++.h>

using namespace std;

const int inf=1e9;
struct edge
{
	int nod,c;
	bool operator <(const edge &aux) const
	{
		return c>aux.c;
	}
};
vector<edge> g[355];
priority_queue<edge> h;
queue<int> q;
int cap_flow[355][355],dist[355],dist1[355],d[355],tata[355];
int n,sursa,dest;
char vaz[355];

void bellman_ford()
{
	for(int i=1;i<=n;i++) dist[i]=inf;
	q.push(sursa);
	dist[sursa]=0;
	vaz[sursa]=1;
	while(!q.empty())
	{
		int nod=q.front();
		q.pop();
		vaz[nod]=0;
		for(auto vec : g[nod])
			if(cap_flow[nod][vec.nod] &&
			   dist[nod]+vec.c<dist[vec.nod])
			{
				dist[vec.nod]=dist[nod]+vec.c;
				if(vec.nod!=dest && !vaz[vec.nod])
				{
					q.push(vec.nod);
					vaz[vec.nod]=1;
				}
			}
	}
}

int dijkstra()
{
	for(int i=1;i<=n;i++) d[i]=dist1[i]=inf;
	d[sursa]=dist1[sursa]=0;
	h.push({sursa,0});
	while(!h.empty())
	{
		int nod=h.top().nod,c=h.top().c;
		h.pop();
		if(d[nod]!=c) continue;
		for(auto vec : g[nod])
			if(cap_flow[nod][vec.nod] &&
			   d[nod]+dist[nod]+vec.c-dist[vec.nod]<d[vec.nod])
			{
				d[vec.nod]=d[nod]+dist[nod]+vec.c-dist[vec.nod];
				dist1[vec.nod]=dist1[nod]+vec.c;
				tata[vec.nod]=nod;
				if(vec.nod!=dest) h.push({vec.nod,d[vec.nod]});
			}
	}
	for(int i=1;i<=n;i++) dist[i]=dist1[i];
	return d[dest]<inf;
}

int main()
{
	freopen("fmcm.in", "r" ,stdin);
	freopen("fmcm.out", "w", stdout);
	int m,sol=0;
	scanf("%d%d%d%d",&n,&m,&sursa,&dest);
	for(int i=1;i<=m;i++)
	{
		int x,y,c,s;
		scanf("%d%d%d%d",&x,&y,&c,&s);
		g[x].push_back({y,s});
		g[y].push_back({x,-s});
		cap_flow[x][y]=c;
	}
	bellman_ford();
	while(dijkstra())
	{
		int s=inf;
		for(int nod=dest;nod!=sursa;nod=tata[nod])
			s=min(s,cap_flow[tata[nod]][nod]);
		for(int nod=dest;nod!=sursa;nod=tata[nod])
		{
			cap_flow[tata[nod]][nod]-=s;
			cap_flow[nod][tata[nod]]+=s;
		}
		sol+=s*dist[dest];
	}
	printf("%d",sol);
	return 0;
}