#include <cstdio>
#include <vector>
#include <queue>

using namespace std;

const int inf=1000000000;
struct heap
{
    int nod,c;
    bool operator <(const heap &aux) const
    {
        return c>aux.c;
    }
};
vector<int> v[355];
queue<int> q;
priority_queue<heap> h;
int cost[355][355],dist[355],cap[355][355],flow[355][355],d[355],tata[355],sursa,dest,n;
char vaz[355];

void bellman_ford(int nod)
{
    for(int i=1;i<=n;i++) dist[i]=inf;
    dist[nod]=0;
    q.push(nod);
    vaz[nod]=1;
    while(!q.empty())
    {
        int nod=q.front();q.pop();
        vaz[nod]=0;
        for(vector<int>::iterator it=v[nod].begin();it!=v[nod].end();it++)
            if(cap[nod][*it] && dist[*it]>dist[nod]+cost[nod][*it])
            {
                dist[*it]=dist[nod]+cost[nod][*it];
                if(!vaz[*it] && *it!=dest)
                {
                    vaz[*it]=1;
                    q.push(*it);
                }
            }
    }
}

int dijkstra()
{
    for(int i=1;i<=n;i++) d[i]=inf;
    d[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<int>::iterator it=v[nod].begin();it!=v[nod].end();it++)
            if(cap[nod][*it]>flow[nod][*it] && d[*it]>d[nod]+cost[nod][*it])
            {
                d[*it]=d[nod]+cost[nod][*it];
                tata[*it]=nod;
                if(*it!=dest) h.push({*it,d[*it]});
            }
    }
    return d[dest]!=inf;
}

int main()
{
    freopen("fmcm.in", "r", stdin);
    freopen("fmcm.out", "w", stdout);
    int m,x,y,a,c,sol=0;
    scanf("%d%d%d%d",&n,&m,&sursa,&dest);
    for(int i=1;i<=m;i++)
    {
        scanf("%d%d%d%d",&x,&y,&a,&c);
        v[x].push_back(y);
        v[y].push_back(x);
        cap[x][y]=a;
        cost[x][y]=c;
        cost[y][x]=-c;
    }
    bellman_ford(sursa);
    for(int i=1;i<=n;i++)
        for(vector<int>::iterator it=v[i].begin();it!=v[i].end();it++)
            cost[i][*it]+=dist[i]-dist[*it];
    while(dijkstra())
    {
        int s=inf;
        for(int i=dest;i!=sursa;i=tata[i]) s=min(s,cap[tata[i]][i]-flow[tata[i]][i]);
        for(int i=dest;i!=sursa;i=tata[i])
        {
            flow[tata[i]][i]+=s;
            flow[i][tata[i]]-=s;
        }
        sol+=s*(d[dest]-dist[sursa]+dist[dest]);
    }
    printf("%d",sol);
    return 0;
}