#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],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(vector<edge>::iterator it=g[nod].begin();it!=g[nod].end();it++)
if(cap_flow[nod][it->nod] && dist[nod]+it->c<dist[it->nod])
{
dist[it->nod]=dist[nod]+it->c;
if(it->nod!=dest && !vaz[it->nod])
{
q.push(it->nod);
vaz[it->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(vector<edge>::iterator it=g[nod].begin();it!=g[nod].end();it++)
if(cap_flow[nod][it->nod] && d[nod]+dist[nod]+it->c-dist[it->nod]<d[it->nod])
{
d[it->nod]=d[nod]+dist[nod]+it->c-dist[it->nod];
dist1[it->nod]=dist1[nod]+it->c;
tata[it->nod]=nod;
if(it->nod!=dest) h.push({it->nod,d[it->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;
}